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Virginia’s
Clear Skies
and
Stormy Weather
When
it comes to climate, we Virginians are considered
blessed. The Old Dominion’s weather has sometimes
been described as the “Goldilocks Climate” –
neither too hot nor too cold, but just about right.
In
fact, it is quite diverse. According to the Virginia
State Climatology Office, the state has five
different climate areas--the Tidewater, Piedmont,
Northern Virginia, Western Mountain and Southwestern
Mountain regions. Temperatures can range from
moderate in areas such as Charlottesville, Warrenton
and Lynchburg to bitter cold in the northern Blue
Ridge. Rainfall averages vary from a low of 33
inches in the Shenandoah Valley to more than 60
inches in Virginia’s southwestern mountains.
(Source: Virginia
State Climatology Office.)
You
can credit three factors: the Atlantic Ocean and its
warm Gulf Stream; the Blue Ridge and Appalachian
mountain systems; and the Commonwealth’s odd
waterways--rivers that run north, south, east and
west--with the state’s diverse weather. The
northeast trajectory of storms that reach the coast
occurs because the air over cold land hits the warm
Gulf Stream and parallels the coast and the jet
stream. The driest areas of the state are the
Shenandoah and New River valleys because they are
trapped between the two mountain chains. Moist air
coming from either west or east drops on the far
slopes before it reaches those valleys.
In
addition to flowing over mountains and into valleys,
air also flows up river valleys in Virginia, so
depending on which way a river flows, weather
patterns change. For example, in far southwestern
Virginia, the Holston River drains south into North
Carolina and Tennessee. A flow of air from the south
would move up the river’s drainage area and rain
would increase up river at higher elevations. And we
wonder why the weather people can’t get it right.
But
weather prediction was even an avocation for our
founding fathers. James Madison may have been the
Commonwealth’s earliest weatherman. At the request
of Thomas Jefferson, Madison jotted down more than
16,000 weather observations at his Montpelier
plantation over an 18-year-period between 1784 and
1802. Slightly 200 years later, in 2003, researchers
from the University of Virginia and the University
of Arkansas used those observations to determine
that spring rains came a month earlier--in May,
rather than June--in the colonial period in central
Virginia. To determine these historical weather
conditions they matched Madison’s notes to the
width of growth rings on original oaks on his
property. Wider rings usually mean more
precipitation. “These were guys who lived the
ideals of the enlightenment,” said one of the
researchers in a March 27, 2003 article in UVA’s
student newspaper, The Cavalier Daily. Jefferson’s
and Madison’s records met the highest scientific
standards of the time, he added.
While
Madison’s observations documented the more mundane
day-to-day weather changes, Virginia does experience
its share of weather extremes. Take hurricanes, for
example. The Virginia Department of Emergency
Management reports that since 1871, 123 hurricanes
or tropical storms have hit Virginia at a cost of
228 lives. One of the earliest recorded hurricanes
occurred on September 6, 1667. It is reported that
the Chesapeake Bay rose 12 feet and the storm caused
the widening of the coastal Lynnhaven River near
present day Virginia Beach. The hurricane that
caused the most damage was Camille in 1969. It
dropped 31 inches of rain in just 12 hours south of
Charlottesville. Mud slides and flash flooding
resulted, killing at least 153 people, the majority
in Nelson County. More than 100 bridges were washed
out in the area, as well.
Hurricanes
Hurricanes often spawn tornadoes. In 1979 Hurricane
David spawned the most –eight in Virginia alone.
Tornadoes can also develop from thunderstorms.
According to the Southeast Regional Climate Center,
Virginia experiences an average of seven tornadoes
per year with an average of one death and 10
injuries. The most tornadoes – 28 – occurred in
1993. The worst tornado dates from May 2, 1929 when
a tornado struck Rye Cove in Scott County, killing
13 people. A more recent tornado in 1993 killed 4
and injured 238 in Petersburg. Winds were estimated
at 225 mph in the downtown area. (See Tornadoes
of Virginia.)
The
Commonwealth has experienced other weather extremes
as well. The highest temperature ever recorded was
110o F. in Balcony Falls in Rockbridge County on
July 15, 1954; the lowest is -30o F on January 21,
1985, at the Mountain Lake Biological Station near
Blacksburg. Big Meadows, along the Skyline Drive,
holds the record for the greatest snowfall during a
single storm: 48 inches fell January 6-7, 1996. The
most snow to fall in a month occurred in Warrenton
in February 1899, when fifty-four inches fell. (See Virginia
Extremes.)
And
Virginia shares one extremely odd weather phenomenon
with only one other place in the world.
Peter's Mountain, which straddles the Virginia/West
Virginia border in Alleghany County, is known
throughout the world by meteorologists. In the
spring, when conditions
are right, a great roaring wind is heard, described
by one as "a tremendous thundering roar of
giant waves breaking over rocky reefs." The
phenomena occurs in only one other location--on the
island of Penang, off the Malay Peninsula.
NEXT
TIME: Below the Surface: Or What the Heck Is
Vermiculite?
--
May 23, 2005
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