"Superstorm" Sandy - Two Years Later

 

Sandy's Track (source: National Hurricane Center)

Wednesday marked the second anniversary of Sandy making landfall on the U.S. East Coast.  It was a devastating storm being both deadly and destructive.  It was also exceptionally rare for where it made landfall in southern New Jersey.  The effects of Sandy were widespread and far-reaching.  In many parts of New York and New Jersey, repairs are still being made.  To read more about Sandy, take a look at this article I wrote for the WUSA9 website.

The Urban Heat Island Effect

View of Washington, DC from space

During the fall months as temperatures begin to cool it is quite common to see a larger range in daytime temperatures.  When the air is drier, it’s easier for it to cool and heat up than it is when the air is more humid.

Another factor that contributes to a high degree of variability between morning lows and daytime highs is the geography of a given region.  Given uniform atmospheric conditions, a rural area will cool off more quickly than an urban area.  Conversely, an urban area will heat up more quickly than a rural area.  This is known as the “Urban Heat Island” effect.  

The Nation’s Capital experiences the “Urban Heat Island” effect often during the fall months.  On the water near the center of town, National Airport is often much warmer at night than the more rural Dulles Airport since the rural area does not capture heat during the day that way the concrete and buildings do in a big city.  Since there is more vegetation around Dulles Airport that absorbs less heat, Dulles also cools off more quickly at night.

We just saw a good example of this yesterday.  Although only a relatively short geographic distance exists between the two airports, yesterday’s morning low at National Airport was 46 degrees while it cooled to a frosty 33 degrees at Dulles.  Being a quiet weather day, this significant difference in temperature can be attributed to the “Urban Heat Island” effect.

Remembering Wilma and other Fierce Hurricanes

Hurricane Dean in August 2007

Today marks the 9^thanniversary of when Hurricane Wilma made landfall on the West coast of Florida. Although at one point, Wilma was the strongest hurricane on record in the Atlantic, it weakened to a Category 3 before making landfall in Florida. Wilma is also significant for being the last major hurricane (Category 3, 4 or 5) to make landfall in the United States.

That’s not to say there haven’t been major hurricanes in the Atlantic Ocean since then or storms that have caused widespread damage in the United States. There were two Category 5 hurricanes in 2007 (Dean and Felix), but neither one had a direct impact.  In 2008, Hurricane Ike was a Category 2 hurricane that caused widespread damage in Texas.  Being a large hurricane, Ike also caused a large storm surge – in excess of 15 feet in places – when it made landfall.

The geographic size of a hurricane doesn’t always equate to intensity. Hurricane Andrew had a relatively small diameter in 1992 but will forever be remembered as only the third Category 5 hurricane to make landfall in the United States. Ike and Andrew are both among the costliest natural disasters in U.S. history.

Hurricane Irene came ashore in late August 2011 and caused extensive damage and flooding in the Mid-Atlantic and Northeastern U.S.  Irene was a major Category 3 hurricane while over the ocean, but weakened to a Category 1 before making landfall.  Sandy affected many of the same areas in late October 2012 and was second only to Hurricane Katrina in the amount of damage it caused.  Sandy set several rainfall records in the Mid-Atlantic Region. 

Hurricane Arthur came ashore in the Outer Banks of North Carolina earlier this year as a Category 2.  However, it has been nine years now since a major hurricane has made landfall anywhere in the United States and since Wilma caused extensive damage in Florida.

Changeable Fall Weather

As is symbolic of the changing seasons, wide variations in hot and cold weather (as well as wet and dry weather) are quite common in the middle latitudes.  In the Mid-Atlantic Region, such extremes are especially common during the fall months.

2014:  A severe weather outbreak occurred last week across the Midwestern and Eastern United States.  Although not as frequent as in the spring, the fall also has severe weather.  From October 12 through October 15, there were more than three dozen confirmed tornadoes; including the first October tornado fatalities in the United States since 2009.  

Two of the tornadoes touched down locally with one near Alexandria, VA and another in Howard County, MD.  They were both weak with estimated winds of 55 - 65 mph making them each an EF-0 on the Enhanced Fujita Scale.  The presence of any of the following makes a thunderstorm “severe” - wind gusts greater than 58 mph, hail at least 1” in diameter, or a tornado.  Overall, there were more than 500 reports of severe weather during the four day period last week. 

2011:  Another demonstration of the seasonal battle that occurs in the Mid-Atlantic during the fall came in 2011.  On October 13, there was a significant severe weather outbreak that included a total of 14 relatively weak tornadoes in central and northern Virginia.  Fortunately, there was no significant damage and no injuries were reported.

2009:  The second of two consecutive record low-high temperatures occurred at National Airport when the high reached only 47 degrees, after it was 45 on October 16.  This coincided with five consecutive days of rainfall for a storm total of 2.6” at National Airport and 2.26” at Dulles Airport.

2007:  Washington, D.C. experienced a record 34 consecutive days without measureable precipitation.  This dry streak ended October 19 when 0.37” fell at National Airport.  What helped keep the Mid-Atlantic so dry for so long was a strong area of high pressure that remained nearly stationary for an extended period of time which kept weather conditions generally sunny and mild.

Weather Quiz

October 19, 2005

Which of these 2005 hurricanes set the all-time record for strongest Atlantic hurricane on this date 9 years ago ?

A.  Emily

B.  Katrina

C.  Wilma

D.  Rita

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Answer to question from October 12:

 

True.  Hurricane Vince became a rare hurricane not far from the Azores but weakened to a tropical depression with sustained winds less than 39 mph before making landfall on October 11, 2005 near Huelva, Spain.