From the ABC 7 Weather team

D.C. Drought And Heat: How Dry And Hot Locally And Nationally

July 13, 2012 - 05:00 AM
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Much of the country is dealing with a severe to extreme drought.  Even locally, abnormally dry conditions persist.  Not only is it dry, but hot, too.  Find out how the two are linked.

You've heard and read about the devastating Colorado wildfires, the crops that are suffering due to the lack of water, and the record breaking heat across much of the country.  All of these devastating events occur because of the heat and drought.  They are both interconnected.  The latest drought monitor was released Thursday, July 12, 2012 and once again, shows much of the country under severe to extreme drought conditions.

U.S. Drought Monitor July 10, 2012

Locally, the Nation's Capital falls under the abnormally dry and moderate criteria.  Parts of the Eastern Shore of Maryland are dealing with a severe drought.

Local Drought from July 10, 2012 Drought Monitor

Not only has it been very dry, but also very HOT!  The recent January to June 2012 period was the warmest for the Mid Atlantic and US in weather records. Take a look at the states that were the warmest on record across the U.S. Both Maryland and Virginia fall into the record warmest category for the 6 month period. 

NCDC State of the Climate

So is there a correlation between the heat and drought?  Well, yes there is.  The two can sometimes "feed" off each other.  Look at it this way:  If the ground and soil are abnormally dry, then the sun heats up the ground faster (there's no water in the ground that the sun needs to evaporate, which is a cooling effect), so the temperature continues to climb.  This process can sometimes continue for days, weeks, and months at a time and this relationship is known as a "positive feedback". 

The presence of a drought can enhance the heat and vice versa.  Another factor that can play into the excessive heat in the summertime, especially, is the Bermuda High.  A Bermuda High is a general area of high pressure that develops over the Atlantic in the summer and can bring the Eastern U.S. a persistent South to Southwest wind flow.  This then pumps up the hot and humid temperatures from the Southeastern states. The graphic below is a good visual of what happens with a Bermuda high offshore:

Courtesy USAToday

A good, soaking rain is very much needed in many of these drought stricken areas, but the weather front that pushed South into the Carolina's Sunday, July 8th, not only brought relief from the wicked heat, but also showers to some of these exceptionally dry areas.  The drought monitor is updated every Tuesday and released every Thursday.  We'll keep you posted on the updated maps. 

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