June was a month of extremes across the U.S. Record heat
dominated the West, where all time record June temperatures were being set in
multiple states. Meanwhile, the same weather pattern that supported the
prolonged, intense heat across the West locked in an extremely wet set up
across the East. Not only were numerous daily rainfall records set, but both
Philadelphia, PA and Macon, GA, ended up with their wettest June ever.
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| Some of the extreme weather across the U.S. in June 2013. Click on image for a larger view. Image Credit: Climate Central. |
You can also add Augusta, GA, to the wettest June on
record. Bush Field in Augusta received
10.83 inches of rain which was 6.11 inches above normal. An observer near
Martinez, northwest of August, received 16.02 inches for June. This is remarkable since that area of Georgia
and South Carolina had been suffering from nearly 3 years of drought until
recently.
Just over a year ago the short-term drought indicator had
the central Savannah River Valley in an exceptional drought. The same indicator now has the region in the
wettest category. The area has gone from
drought to flood in a year’s time, from one extreme to another.
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| Objective short-term drought indicator blend from April 7, 2012 and July 13, 2013. Click on the image for a larger view. Image Credit: NOAA/CPC. |
A number of rivers have flooded across South Carolina due
to the heavy rains this summer. June was
a wet month for the entire state, but July has proved to be even wetter. The maps below show the observed rainfall for
the month of June and for the first 15 days of July. June rainfall was 6.17 in. at the Columbia
Metropolitan Airport, but it was 6.43 in. for July 15.
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| Observed June 2013 rainfall for South Carolina. Click on the image for a larger view. Image Credit: NOAA/AHPS. |
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| Observed rainfall in South Carolina for July 1-14, 2013. Click on the image for a larger view. Image Credit: NOAA/AHPS. |
This has given rise to the thoughts that this may be the
wettest summer ever in Columbia. Not
quite yet. The wettest summer (June,
July, & August) on record was in 1971 when the rainfall total was 29.28 in
(June = 7.46, July = 11.13, & August = 10.69). We are tracking close to the wettest, but
much will depend on August.
Why
is it so wet?
The weather pattern this has been one of a ridge of high
pressure across the West with a trough of low pressure in the East. There have been daily changes, but this has
been the norm this summer. The trough
axis has been west of the Appalachians putting much of the East coast under a
very moist tropical flow. The rain has
been persistent and locally heavy which has contributed to flooding.
In addition, studies have shown that the warmer climate
has led to higher moisture levels in the atmosphere. This tends to get concentrated in the moist
flows from tropical regions. Thus, the
heavy rains may be heavier. Flash floods
are now more likely due to the saturation of the ground.
A torrential downpour hit Columbia this past Sunday
producing an extreme rainfall event.
This resulted in the third highest flood of Rocky Branch Creek. More on this in my next post.
