April 2016: How Will this Month Be Remembered?

Key Bridge and Georgetown University on the horizon

April has been a diverse weather month for Washingtonians this year.  Ironically, it will finish with near-average temperatures.  That means weather records won’t fully capture how exciting this month’s weather has been.

April 2016 can be broken up into two halves.  The first two weeks of the month were significantly cooler than average in the DC Metro Region and snow occurred on three separate occasions.  Low temperatures were in the 30s on six occasions in the Nation’s Capital.  When the temperature fell to 30 degrees at National Airport on April 5, it was the first time it was below freezing in the Nation’s Capital in April since it was 31 degrees on April 4, 2013.  The high temperature of 46 degrees on April 5 was not only significantly below the daily average high of 63, but was also more characteristic of mid-February.  Through April 13, monthly temperatures were more than two degrees colder than average in Washington, D.C.

Conversely, temperatures have been significantly warmer than average for much of the second half of April.  That includes the high temperature of 86 degrees on April 26 at National Airport – more characteristic of June 20.  According to the National Weather Service, that was the warmest April temperature in Washington, D.C. since April 10, 2013 (when it was 91 degrees).  It’s been so much warmer than average during the second half of April that average temperatures went from being more than two degrees cooler than average April 13 to being a degree warmer than average on April 28.  A net swing of more than three degrees in just two weeks’ time is truly remarkable.

This month has also had a touch of severe weather, although, not as much as in past Aprils.  On April 7, there were a few scattered severe wind gusts (i.e. thunderstorms that have wind gusts of at least 58 mph) in parts of the DC Metro Region.  However, the anniversaries of two more significant April severe weather events have gotten attention this week.  Maryland’s strongest tornado on record occurred in La Plata in 2002 and an April outbreak in 2011 brought 19 tornadoes to Maryland and Virginia.

Most of April was drier than average in the Nation’s Capital, but some much-needed rainfall has occurred during the last few days.  Through April 29, 2.03” of rain has occurred this month at National Airport making this the driest April in Washington, D.C., since 2012.  Interestingly enough, high temperatures remained the 50s the last two days and will only approach 60 degrees as April comes to a close – significantly cooler than average – causing average temperatures this month to finish near average.  There hasn’t been a cooler than average April in the Nation’s Capital since 2007.

Weather Quiz

What is the latest observed date in the spring that measureable snowfall has occurred in the Nation’s Capital?

A.  April 15

B.  April 28

C.  May 5

D.  May 16

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Answer to the Weather Quiz question from April 17.

True.  The drier than average start to 2016 has actually continued for much of April in Washington, D.C.  Through April 28, the Nation’s Capital has had 2.02” of rain this month which is nearly an inch below average.

Severe Weather in the Mid-Atlantic Region

Preliminary April 26 Severe Weather Reports (NOAA)

Although the spring is the busiest time of the year for severe weather nationally, Maryland and Virginia typically see a higher amount of severe weather – tornadoes in particular – during the summer.  According to 20-year NOAA averages through 2010, the United States averages more than 1,200 tornadoes annually.  Looking more closely at the data, the months of April, May and June have the highest average number of tornadoes of any three-month period during the year.  Maryland averages 10 tornadoes while Virginia has an annual average of 18 tornadoes. 

In the Mid-Atlantic Region, the highest average number of tornadoes occur in July, August and September.  Part of that is because the weather is warmer and more humid during the summer months which can be more conducive for thunderstorm development.  It also includes the possibility of tornadoes from decaying tropical systems.  There have been a number of former tropical systems during the past twenty years to impact the DC Metro Region with heavy rain, gusty winds, coastal flooding and severe weather – including Fran in 1996, Floyd in 1999, Isabel in 2003 and Irene in 2011.

Meanwhile, the Washington, D.C. – Baltimore corridor has had some significant severe weather events in April during the last fifteen years.  Most recently in 2011, when a total of 19 tornadoes touched down in Maryland and Virginia on April 27-28.  Those tornadoes were a part of a larger four-day severe weather outbreak that occurred from the central United States to the East Coast.  That was one of the highest overall occurrences of tornadoes in the DC Metro Region to occur since April 20, 2008 when nine tornadoes were observed in Maryland and Virginia.

This week also happens to mark the 14^th anniversary of Maryland’s strongest tornado on record. Longtime residents will recall that a powerful F4 tornado touched down in La Plata, Maryland on April 28, 2002.  Although there was advance warning for this storm, this tornado was still damaging and deadly because of its unusual intensity for this part of the country.  During just the last twenty-four hours there has been another significant late April severe weather outbreak.

NOAA’s Storm Prediction Center reports more than 600 cases of severe weather occurred yesterday from Texas to West Virginia.  Such severe weather outbreaks reinforce the need to stay informed of the latest weather conditions.  Social media and smart-phone apps make that easier in 2016 – whereas that wasn’t possible for the La Plata storm in 2002.  Being aware of the latest weather conditions is only part of the story.  Knowing what to do when severe weather or flash flooding threatens your area is equally important to ensure your safety.

A Stellar Month?

Many consider the spring to be the nicest time of the year in the Nation’s Capital.  That’s because after the winter, most are anxious for warmer weather and time outdoors.  There is no shortage of stellar outdoor activities to choose from during the spring in Washington, D.C., whether enjoying the cherry blossoms along the Tidal Basin, to visiting an area museum or monument or taking in a game at Nationals Park. 

Although average temperatures are quite comfortable in the 60s for much of April in Washington, D.C., the weather can sometimes be more reminiscent of winter or serve to foreshadow the upcoming summer.  April 2016 has been no exception with a wide array of weather in the DC Metro Region.  Check out this story I wrote for the WUSA9 website to learn more about what’s made this April an especially memorable weather month.