Weather Quiz

True or False:

Hurricanes, typhoons and cyclones are all the same type of storm.  The only difference between them is the part of the world that they form in.

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Answer to question from July 22^nd:

Due to its larger size – and being the southernmost state in Tornado Alley – Texas averages the most tornadoes (155) annually of the 50 states.  According to the National Climatic Data Center, Kansas has the second highest annual tornado average with 92 tornadoes in a given year while Florida (66) and Illinois (54) are in the Top Ten.   

You Don’t Have to be in Kansas, Anymore

The tornado that touched down this past Friday near Cape Charles, Virginia, makes four consecutive summers that the Mid-Atlantic Region has been hit.  Although outside of “Tornado Alley” (in the central United States where the most tornadoes form), the Mid-Atlantic Region has also been known to see tornadoes on occasion.  According to the National Weather Service, they are most common in this part of the country during the summer months.

The two most conducive weather patterns for tornado formation are when a cold front pushes through the region or when a decaying tropical storm affects the region.  The embedded thunderstorms within the larger rotation of the tropical system often cause relatively weak, short lived tornadoes.  The busiest months of the Atlantic Ocean’s hurricane season are August – October, so Washingtonians will have to wait and see if any tropical systems spawn tornadoes in our region. 
 

The National Climatic Data Center says Maryland averages 10 tornadoes and Virginia averages 18 annually.  Back on June 13, 2013, one of six tornadoes that formed in Maryland and Virginia passed through central Montgomery County, affecting much of Rockville.  They were all relatively weak tornadoes that primarily caused downed trees and power lines.  In contrast, the tornado that formed July 24, 2014 was an EF-1 tornado that struck near a campground on the Southern portion of the Delmarva Peninsula. Sadly, it caused two fatalities and a few dozen injuries.

Tornado intensity is measured on the Enhanced Fujita Scale with rankings from EF-0 (winds 65-85 mph) and EF-1 (86-110 mph), all the way to an EF-5 (winds over 200 mph).  Residents should pay attention to their local meteorologists on days when thunderstorms are forecast.  That way they’ll have the maximum warning when severe weather watches and warnings are issued so they can seek shelter.

July Weather Rollercoaster

The 2014 summer has been wetter than average and featured slightly warmer than average temperatures.  So far, there hasn’t been any prolonged, extreme heat this summer in the Mid-Atlantic Region.  That’s in stark contrast to the torrid summers of 2010 – 2012 which broke all sorts of records.

Triple digit heat in the Nation’s Capital is relatively rare.  Residents may forget that before the three year stretch from 2010 through 2012, triple digit heat had not been felt in Washington, D.C. since 2007.  Before 2010, no summer since 2002 had recorded more than one day of triple digit heat.  That illustrates just how rare the type of heat Washingtonians experienced was during the summers of 2010 – 2012.  In fact, July 2012 had seven days of triple digit heat, breaking the record of six such days set back in July 1930.  

On the opposite end of the spectrum was July 2000.  That was the coolest July ever observed at National Airport, with a monthly average temperature of 74.6 degrees -- 5.4 degrees cooler than average.  

So far, July 2014 has been 0.5 degrees warmer than average.  The Nation’s Capital has also seen nearly 2” more rainfall than average this month.  We’ll have to see if August continues this month’s trend of being wetter and warmer than average.

Weather Quiz

Which state averages the most tornadoes in a given year?

A. Texas

B. Kansas

C. Florida

D. Illinois

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Answer to question from July 14^th:

The presence of any of the above (hail 1” in diameter or greater, wind gusts of at least 58 mph or a tornado) would make a thunderstorm “severe.”  So while no single answer is wrong per se, the correct answer is “D – all of the above” since they would all make a thunderstorm “severe.”

Earliest Category 5 Hurricane on Record

Some may remember a tropical storm named Emily that developed in July 2005.  Little did we know, though, when Emily first developed that it would become a record setting storm.  Emily made three landfalls from the Caribbean Islands to the Yucatan Peninsula to mainland Mexico.

2005 was the busiest hurricane season on record for the Atlantic Basin.  Already the fifth named storm of the young 2005 hurricane season, Tropical Storm Emily became a hurricane July 13.  Continuing to intensify, Emily, on this date 9 years ago, July 16, 2005, became the strongest July hurricane on record.  Emily reached Category 5 status with maximum sustained winds of 160 mph and a minimum central pressure of 929 millibars.

With any tropical storm or hurricane, an inverse relationship exists between air pressure and wind speed where the lower the air pressure in the center of the storm, the higher the winds are around it.   Hurricane Emily was one of four Category 5 hurricanes on record during the 2005 season – along with Katrina, Rita and Wilma – which broke the record for most Category 5 storms in a singular season.

In contrast to 2005, the 2014 season has been much quieter so far with only one named storm.  I mentioned Hurricane Arthur in my July 12 column.  There are currently no systems developing in the tropical Atlantic.  However, that will likely change as we head toward the most active part of the hurricane season from mid-August to mid-October.