Weather Quiz

Hurricane Wilma approaching the SW FL Coast  (Source: NASA)

Hurricane Wilma was the last “major” hurricane (Category 3 or higher) to make landfall in the United States.  In what year did this occur?

      A.     1999

      B.      2005

      C.      2008

      D.     2012

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Answer to Weather Quiz question from June 11.

False.  A warm May can sometimes foreshadow a warmer than average summer, but there no strong correlation exists between a warm May and a warm summer.  The weather pattern that facilitated the warmer than average weather in May could just as easily change to become cooler and/or wetter than average.

How Busy Can June Be?

Tropical Storm Debby's track, June 2012   (Source: NOAA)

Although hurricane season isn’t even a month old, it has already been an active one so far with two named tropical storms: Ana and Bill.  Tropical Storm Ana formed during the second week of May and made landfall near Myrtle Beach, South Carolina.  Tropical Storm Bill made landfall in Texas late last week and its remnants brought prodigious rainfall to the Mid-Atlantic Region this past weekend.  According to the National Hurricane Center, having two named storms before July 1 is relatively unusual in the Atlantic Ocean. 

 

Weather enthusiasts can point to the last above average hurricane season in the Atlantic Ocean (2012) to show how busy things can be early in the season.  On this date in 2012, Debby was named a tropical storm.  Debby was the fourth storm to form before the end of June.  In contrast, the fourth named storm of the 2014 season didn’t come until September 1 when Dolly became a tropical storm.  Contributing to the active start of the 2012 hurricane season were two tropical storms that formed in late May: Alberto and Beryl.  The first hurricane of the 2012 season also developed in June when Chris became a minimal Category 1 hurricane on June 21.

When tropical storm Debby formed in June 2012, it moved slowly for a few days since there was no large scale weather system to help it move more quickly.  That allowed Debby to bring heavy, flooding rains to much of the southeast U.S. Gulf Coast, including most of Florida.  Tampa saw its wettest June on record three years ago with a monthly rainfall total of 18.66”.  Worst of all, Tampa set a daily rainfall record of 7.11” on June 24, 2012.  That’s more rain than Tampa typically sees during the entire month of June.  Although, tropical storm Debby never achieved hurricane status, it caused roughly $250 million in damage – largely the result of flooding.

This underscores the point that a tropical storm or hurricane doesn’t have to be exceptionally strong to cause major flooding or damage as Bill has demonstrated during the last several days.  This season’s next tropical storm will be named Claudette.

Remembering Agnes 43 years later

Mid-Atlantic rainfall totals from Agnes  (Source: NOAA)

On this date in 1972, the nation’s capital saw its largest June daily rainfall on record and experienced severe flooding because of former Hurricane Agnes. In fact, the entire Mid-Atlantic Region got record breaking rainfall that caused devastating flooding. Although Agnes was only a minimal Category 1 hurricane when it made landfall along the U.S. Gulf Coast, winds were never its most damaging component.

In the DC Metro Region, Agnes brought a total of nearly 8.2” of rain to National Airport (with 6.11” falling on June 21) while Dulles Airport in nearby Sterling, Virginia, saw a storm total of 13.65” (including a daily rainfall record of 10.67” on June 21). This copious rainfall flooded an untold number roads and washed away some area bridges. The Potomac River at Little Falls crested more than 12 feet above flood stage according to the U.S. Geological Survey. As bad as the flooding was in the nation’s capital, it was even worse in Pennsylvania where it caused a dike to breach in Wilkes-Barre that almost destroyed the entire town.

Although most of the flooding and damage from Agnes resulted when it was no longer a hurricane, Agnes was the first Category 1 hurricane to have its name retired. Agnes claimed 122 lives in the United States and caused $15.9 billion in damages (2024 dollars).  Agnes demonstrated that tropical storms and hurricanes do not have to be intense to have a high death toll or cause a lot of damage.  

Just yesterday, the remnants of Tropical Storm Bill contributed to the copious amount of rainfall in the Mid-Atlantic Region.  A daily record 2.37” of rain fell at National Airport yesterday during what has also been a wetter than average June.

Putting this week's Heat Wave into Perspective

Keeping cool in a comfortable spot in Washington, D.C.  (June 2015)

Although this past week was the hottest of the year and featured the longest heat wave in nearly two years, no new record highs were set. On Tuesday, June 16 the temperature reached 96 degrees, which was the hottest temperature in the Nation’s Capital since August 31, 2014.

This week’s heat wave began on June 11 and continued through Tuesday, June 16. Washingtonians have to go back to 2013 to find the last stretch of six or more 90 degree days (July 15 –21).  That’s why residents of the Nation’s Capital are correct to say that the weather has been unusually hot of late. However, it hasn’t been unprecedented.  Area residents endured triple digit heat in three consecutive Junes starting in 2010.  The hottest June temperature on record in Washington, D.C. occurred in that time when it was 104 degrees on June 29, 2012.

This spring was relatively short in the Mid-Atlantic Region with below average temperatures spanning most of March, while May was the warmest on record downtown. Data from the National Weather Service indicates this month has been more than 3 degrees warmer than average in the Nation’s Capital through June 17.  However, this month hasn’t approached the degree of heat that the warmest June on record (2010) featured.

The weather pattern became very summer-like last month because the “Bermuda High” set up earlier in the season than it normally does. The Bermuda High is a semi-permanent area of high pressure that typically sits off the East Coast of the United States during the summer months. This allows it to pump warm and humid air from the Deep South into the Mid-Atlantic Region. It’s known as the “Bermuda High” since that’s where it’s typically centered.

When the U.S. Climate Prediction Center issued the temperature outlook for June, it called for above average temperatures across the Mid-Atlantic Region. In fact, the 90s are poised to return early next week in the Nation’s Capital.  Average high temperatures during the second half of June only range from the mid to upper 80s.

It’s important to note that a warmer than average June doesn’t necessarily mean the entire summer will be warmer than average.  For instance, last June was warmer than average in the Nation’s Capital, but the average temperatures for July and August 2014 were both within a half degree of “average.”  My colleagues and I on the WUSA9 Weather Team will keep you posted on the latest weather forecasts as the summer progresses.

Does Hot Weather in June have any Special Significance?

Glen Echo, Maryland (June 2015)

Following the warmest May on record in the Nation’s Capital, the first half of June has also been warmer than average.  However, temperatures so far this month haven’t been as far above average as they were in May.  That said, the Mid-Atlantic Region is currently in the hottest stretch of weather to date of 2015.  Although no record highs were broken this week in the Nation’s Capital, some have been threatened. 

 

A “heat wave” is defined by meteorologists as a streak of at least three consecutive days with temperatures of 90 degrees or hotter.  Washingtonians experienced their first heat wave of the season from May 30 through June 1.  However, that was followed by four consecutive days of below average temperatures.  In fact, the high temperature on June 3 at National Airport (the official weather reporting site in the Nation’s Capital) was only 64 degrees which is the average high on April 7. 

Meanwhile, the pendulum has swung back the other way as today will be the 4^th consecutive day with temperatures in the 90s in the Mid-Atlantic Region.  Although some record high temperatures may be approached (particularly at Dulles Airport where weather records only go back to the 1960s), no record highs are likely to be broken the next few days.  The hottest temperature so far this year in the Nation’s Capital was 94 degrees on June 12.  That was Washington, D.C.’s hottest temperature since it was 95 degrees on September 6, 2014.

Some may wonder if a warmer than average May and June will translate to a warmer than average summer.   Although above average temperatures in May and June have on occasion served to foreshadow above average temperatures, that isn’t always the case.  For example, in a truly rare occurrence, June 2000 saw more 90 degree heat than July 2000 in the Nation’s Capital: five days compared to one day.  In fact, July 2000 saw nine days with high temperatures only in the 70s – more characteristic of May than July.  So a warm June doesn’t always correlate to a warmer than average summer.

National Weather Service data indicates that June 2010 was the warmest June on record in the Nation’s Capital.  That proved to be a harbinger of the rest of the summer as July 2010 finished tied for the third warmest on record in Washington, D.C., and above average temperatures continued in August and September 2010.  This illustrates that a warmer than average June can sometimes be a harbinger of what the entire summer may entail.

Meteorologists and climate scientists look at global weather patterns when issuing seasonal forecasts – such as the presence of El Nino – and the associated effects that occur around the world.  The U.S. Climate Prediction Center is expecting warmer than average temperatures to continue for the rest of June in the Mid-Atlantic Region.