Saturday, August 17, 2013

August 2013 - Wet & Seasonally Cool


Summer 2013
Longhorn Milkweed Beetles 
( Tetraopes tetrophthalmus )
Photograph by Harold L. Jerrell - © All Rights Reserved.

A wet & seasonally cool weather pattern dominated the first half of August 2013 as the glory of Mother Nature increased NOISE levels across the mountain landscape. 


August is the month of SOUND.

This reminds me of a column I wrote some years ago:
When night falls upon the ancient Cumberlands the hum of cicadas and the twittering of songbirds cease, as a multitude of new sounds emerge to fill their voids!

   If you have lately been outside near nightfall, or even listened closely from inside, you have likely heard a great chorus of sounds coming from seemingly every nook and cranny!

   While some of these sounds are from Black Field and Green Tree Crickets, most of the loud thrills are from a group of American Long-horned Grasshoppers commonly called Katydids.
   The variable and rather extreme weather patterns of spring-summer seem to have been favorable for the development of a large population of Eastern Katydids or, as my grandparents used to call them, Sawyers!

   While there are many different species of Katydids, the ones that tend to stimulate eardrums most often are the robust Coneheaded Katydids whose sounds can travel a third of a mile, if not more, under ideal conditions.  They are, without question, the overwhelming "noise" makers of the night ( no disrespect to my beloved Barred & Screech Owls ).

   Some Katydids live in trees, while others prefer grass and ground vegetation.  Although most are green and blend well with the summer foliage, some species have brown, pink, or even rarely orange colorations. 

   Most male Katydids make their long stretched out thrills, and pulsating sounds, by rubbing together ridges and rough places located near the base of their outer wings.

   Varying arrangements of these ridges and rough places yield different sounds, thereby distinguishing different species.
  Incredible, yes indeed!

   The first Sawyers actually began to fill the nights with sound during mid to late July, so according to mountain tradition the first frost can be expected in early September.

While that may be questionable, there is little doubt that August in the ancient Cumberlands is truly, from day to night, a month of sound!

Common Butterfly-weed
( Asclepias tuberosa var. tuberosa )
Photograph by Wayne Browning - © All Rights Reserved.


Climate Statistics
For August 1-15, 2013

( Lower Elevations of Russell Fork Basin )
Clintwood 1 W - Elevation 1560 feet
Average Daily MAX: 76.7 degrees
Average Daily MIN: 61.5 degrees
MEAN: 69.1 degrees
Highest Temperature: 82 degrees
Lowest Temperature: 49 degrees
August 1-15 Rainfall: 3.69"
2013 Precipitation: 36.36"

( Northern Base of High Knob Massif )
City of Norton - Elevation 2141 feet
Average Daily MAX: 76.0 degrees
Average Daily MIN: 58.2 degrees
MEAN: 67.1 degrees
Highest Temperature: 81 degrees
Lowest Temperature: 45 degrees
August 1-15 Rainfall: 3.15"
2013 Precipitation: 45.80"

( Along the Tennessee Valley Divide )
Nora 4 SSE - Elevation 2650 feet
Average Daily MAX: 75.1 degrees
Average Daily MIN: 61.1 degrees
MEAN: 68.1 degrees
Highest Temperature: 79 degrees
Lowest Temperature: 51 degrees
August 1-15 Rainfall: 3.40"
2013 Precipitation: 42.26"

The first half of August produced a general 3.00" 
to 5.00" of rainfall across the High Knob Massif and surrounding region, with heaviest amounts generally along and west of the Appalachians on westerly dominated air flow trajectories ( verses along and east of the mountain chain during 
July on prolonged easterly component air flow ).

Gary Hampton reported one of the heavier rainfall totals during the first half of August with 5.47" being measured by him and staff of the 
Big Stone Gap Water Plant.

August 2013 Rainfall Days
Big Stone Gap Water Plant
Observer: Gary Hampton & Staff
( South Fork Gorge of High Knob Massif )
Elevation 1965 feet

08-01-2013  0.44"

 08-03-2013  0.06"

 08-06-2013  0.01"

 08-08-2013  0.69"
08-09-2013  0.57"
08-10-2013  1.41"
08-11-2013  0.52"
08-12-2013  0.88"
08-13-2013  0.75"
08-14-2013  0.14"

August 1-14 Total: 5.47"

Total Since June 1: 20.26"

2013 Total: 50.21"

12-Month Total: 70.30"
( August 15, 2012 - August 14, 2013 )

With a general 20.00" to 25.00" of summer rain in South Fork of the Powell River Basin to August 15, there had been plenty of rainfall to keep Big Cherry Lake overflowing its spillway all summer. 

Big Cherry Dam is 2.0 air miles ENE of the Big Stone Gap
Water Plant ( and is 1155 vertical feet higher in elevation ).

( Centered on Virginia )
Doppler Estimated Rainfall During August 1-17, 2013

A bias toward westerly air flow trajectories being generalized in the rainfall pattern given the chaotic nature of convection which continued to dominate the precipitation mode.

( Centered on Tennessee )
Doppler Estimated Rainfall During August 1-17, 2013

The general WNW air flow trajectory during 
August 1-15 is visible on this 850 MB Composite.

August 1-15, 2013
Composite Mean 850 MB Wind Vectors

This represented a radical shift from the 
mean flow that dominated the July 1-24 period.

July 1-24, 2013
Composite Mean 850 MB Wind Vectors

Looking at Summer 2013 up to now, the 850 MB vector wind anomaly verses that of observed climatology reveals one factor driving excessive wetness along and east of the Appalachians.

June 1 to August 15, 2013
Composite Mean 850 MB Wind Vector Anomaly

Mean air flow has been dominated by trajectories off the Atlantic Ocean into the region from the Blue Ridge to Tidewater instead of from the Gulf of Mexico.  In other words, mean westerly air flow components that generate some drying with descent leeward of the Appalachians have been much less common this summer.

( 1981 to 2010 Climate Period )
 850 MB Wind Vector Climatology


Summer Taste of Autumn

Several notable cold frontal passages since July 24 have generated numerous chilly nights, especially amid higher mountain valleys.

First Jewelweeds Beginning To Bloom
Orange Spotted Jewelweed ( Impatiens capensis )
Photograph by Wayne Browning - © All Rights Reserved.

A certain sign that autumn is not far away, along with Katydids, is marked by the blooming of Orange Spotted & Yellow ( Impatiens pallida ) Jewelweeds.

Jewelweeds, also called Touch-Me-Nots for their seed pods that literally explode when touched by anything upon ripening, are 
a favorite late summer and early autumn wildflower of 
Ruby-throated Hummingbirds ( Archilochus colubris ).


MINS By The Numbers
Chilly Mornings In The City of Norton
( and higher valleys at 2400-3500 feet ) 

July 26
50 degrees
( mid-upper 40s )

July 29
46 degrees
 ( low-middle 40s )

July 30
48 degrees
( mid-upper 40s )

August 5
53 degrees
( upper 40s-lower 50s )

August 15
45 degrees
*( 40 to 45 degrees )

August 16
52 degrees
( upper 40s-lower 50s )

Minimums dropped to around 40 degrees in coldest valleys from the High Knob Massif to Burkes Garden into morning hours of August 15, marking the coolest night of Summer 2013.

*This was not a record.  Record lows for August 15 reached 
30 degrees in Burkes Garden during 1924 ( data period 1896-Present ) and 41 degrees in Wise ( data period 1955-Present ).

Summer 2013
Granddaddy Longlegs ( Opilione ) & Company
Photograph by Harold L. Jerrell - © All Rights Reserved.

Although records were not set, an interesting aspect of the mid-August cool spell was the formation of cold air advection upslope clouds during overnight-morning hours of August 14.

NASA Visible Image At 7:45 AM on August 14, 2013

A thick bank of upslope clouds formed along windward sides 
of the High Knob Massif - Black Mountain and Tennessee Valley Divide corridor northeast to around Flattop in West Virginia, as well as along windward ( with respect to NNW-N air flow ) slopes of higher portions of Clinch Mountain, Whitetop-Mount Rogers, and the TN-NC border.  Also note river valley fog across much of West Virginia and frontal zone cloudiness lee of the Appalachians in North Carolina and southeastern Virginia.

NASA Visible Image At 7:45 AM on August 14, 2013

NASA Visible Image At 8:32 AM on August 14, 2013

This section is under construction.  Check back for updates.
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