Monday, February 12, 2018

Late Winter 2018 In The High Knob Massif

February 9, 2018
Snow Covered High Knob Lake Basin
Looking To Roan Mountain From High Knob
Photograph by Wayne Browning - © All Rights Reserved

The famed Mountain Empire was in fine form as viewed from the summit level of the High Knob Massif on Friday ( February 9 ).  The only problem, 
a good amount of snow remained on slopes in the high country ( visible through trees across lower half 
of photograph ) in advance of a major rainfall event.

( Large section - Allow Time To Load )

February 9, 2018
Looking SE From High Knob Lookout
Snow Covered High Knob Lake Basin
Photograph by Wayne Browning - © All Rights Reserved

Using a long telephoto lens a ski slope on top of Beech Mountain in western North Carolina was visible, along with the stoic profile of adjacent Grandfather Mountain.

February 9, 2018
The Mountain Empire Region
Photograph by Wayne Browning - © All Rights Reserved

A field trip as part of the undergraduate research program at the University Of Virginia's College At Wise set out to see how much snow remained in the high country of the massif in advance of a major precipitation event.

February 9, 2018
UVA-Wise Undergraduate Research Students
Kendall Morse & Kyle Hill In The High Country 
Photograph by Wayne Browning - © All Rights Reserved

Extensive snow cover was visible from Bowman Mountain, which wraps around the head of Clear Creek Basin, southwest across the peaks of High Knob, Eagle Knob, and Little Mountain Knob to Big Cherry Lake Dam ( miles SW of the main peak ).

February 9, 2018
High Knob Lake Basin
Looking North Toward The High Knob Peak
Photograph by Wayne Browning - © All Rights Reserved

A prime objective, of course, was not just to look at the snow coverage but to take a core sample to see just how much water content remained locked in the lingering 3" to 5" snowpack, with numerous 
6-12" drifts from High Knob to Big Cherry Dam. 

*The snowpack had diminished from around 10" of
mean depth early in February, with much bigger drifts
as illustrated by the occasional 6-12" drifts observed.

February 9, 2018
Snow Along State Route 619
High Country of High Knob Massif
Photograph by Wayne Browning - © All Rights Reserved

A clean snow core found a concentrated amount of moisture that equaled to 0.40" of water content per 1" of snow depth ( a density of 2.5:1 ).

This translated to a general 1.00" to 2.00" of water locked up in the snow when not counting the larger snow drifts.

February 9, 2018
Central Appalachian Northern Hardwoods
Snow Covered High Knob Lake Basin
Photograph by Wayne Browning - © All Rights Reserved

While 1.00" to 2.00" of water content would not typically be that big of deal, around 3.00" of total precipitation had already fallen in the high country during the first week of February.

This pushed whitewater creeks draining the massif above flood stage, with initial snow melt.

Big Stony Creek Stream Level History

Ice was visible on the upper end of Big Cherry Lake from High Knob Lookout and although snow is not clearly visible in this light a considerable amount remained through the woods surrounding the lake 
( with local drifts ).

February 9, 2018
High Knob High Country
Water Elevation of Lake 3120 Feet
Looking Across Big Cherry Lake Basin
Photograph by Wayne Browning - © All Rights Reserved

Packed ice and snow remained on Big Cherry Lake road, downstream from the Dam toward Big Stone Gap Water Plant, at elevations above 2700 to 3000 feet.  Note a tiny section of the ice covered upper portion of the lake is 
visible in the above photograph.

Total precipitation at Big Cherry Lake Dam during the January 1 to February 9 period totaled 8.08" on the NWS rain gauge; however, this was somewhat low due to wind induced undercatches as air blows across the Dam ( with substantial losses during periods of frozen precipitation ).

February 14, 2018
South Fork Gorge of High Knob Massif
Photograph by Wayne Browning - © All Rights Reserved

It was so dark by the time we reached this location that no color was visible, so I shot the photograph in black-and-white using a long time exposure.

South Fork of Powell goes subterranean in places so when it is flowing completely above ground that is not a good sign in front of a major rainfall event, since that indicates underground conduits are full of water and will not be able to handle extra input.

Flood Of February 2018

Preliminary List Of Rainfall Totals

Georges Fork: 3.80"
( John Mullins )

*Clintwood 1 W: 4.06"

Big Stony Creek IFLOWS: 4.14"
( SE Base of High Knob Massif )

Fort Blackmore IFLOWS: 4.16"

Herald IFLOWS: 4.31"
( Sandy Ridge )

Pole Bridge Road: 4.54"
( Layton Gardner - Wise )

Stone Creek IFLOWS: 4.78"
( Lee County )

City of Norton: 4.93"
( Jimmy Fawbush )

Little Mountain IFLOWS: 5.24"
( Route 237 )

Ben Hur IFLOWS: 5.24"
( Lee County )

Appalachia Lake Water Plant: 5.29"
( Mark Quillin & Staff )

Black Mountain Mesonet: 5.35"
( Near Harlan-Wise Line )

*Big Cherry Dam IFLOWS: 5.87"

Big Stone Gap Water Plant: 5.97"
( Gary Hampton & Staff )

Big Cherry Dam NWS Gauge: 6.60"
( 15.45" January 1-February 14 )

*Robinson Knob IFLOWS: 6.85"
( High Chaparral-Robinson Knob )

*Updated for final storm totals.

The worst flooding developed downstream from creeks that originated in the snow covered High Knob Massif, so collection of snow core data prior to this event proved important as it allowed for better resolution of how much moisture input actually contributed to flooding.

In Wise County
Worst flooding developed along the Ramsey, Tacoma to Coeburn valley corridor after input from Clear Creek, Machine Creek and Burns Creek added greatly to the flow volume of Guest River, and within the Cracker Neck-East Stone Gap to Big Stone Gap valley corridor with input from South Fork of the Powell draining Big Cherry Lake basin 
( the Dam at Big Cherry Lake helping, of course, to reduce total run-off ).  The South Fork drains 40 square miles.

In Scott County
Some of the worst flooding developed from the Ka-Fort Blackmore area downstream as huge volume from the 41.9 square mile Big Stony Creek basin was added to this area.

Using just automated rain gauge data for a preliminary look, the effective input from snow covered basin heads where Big Stony Creek, South Fork of Powell and Clear Creek forms was on the order of 7.00" to 8.00" of water ( rainfall + around 1.50" from snow melt ).

It is amazing ( incredible really ) that flooding was not more severe, and without question this was due to a huge amount of water input originating within basins possessing heavily forested, intact watersheds within the High Knob Massif.

Beauty & The Beast

February 11, 2018
The BEAST of The South Fork
South Fork Gorge At Big Stone Gap WP
Adam Herron iPhone Video

Veteran water plant technician Adam Herron captured this tremendous flow of water, which threatened to overtake the Big Stone Gap Water Plant, as it gushed downward through South Fork Gorge at around 9 AM on February 11. 

South Fork of Powell River drops 1433 vertical feet 
in 4 miles downstream of Big Cherry Dam.

It is an American Whitewater Rated Class V+ steep creek.  No one can understand the sheer power of these creeks unless being near them.  It is simply INCREDIBLE!

February 14, 2018
The BEAUTY of The South Fork
Photograph by Wayne Browning - © All Rights Reserved

Adam's video is of this same view ( as well as my previous black-and-white pre-storm photograph ), but near peak flow volume during the flood.

A total of 5.79" of rain was hand-measured at the Big Stone Gap Water Plant during this event, with approximately 6.60" falling at Big Cherry Dam 
( more rain fell during February 14 before I measured the NWS gauge ).

Big Cherry Dam was closed to discharge during the flood, of course, and remained closed throughout February 14 with flow seen in these photographs being driven by spillway overflow and run-off.

Big Stone Gap Water Plant
Superintendent Gary Hampton & Staff
Rainfall Totals ( 9:00 AM Daily )

February 2:  0.71

February 4:  0.31
February 5:  0.56

February 7:  1.02
February 8:  0.31

February 10: 0.79
February 11: 4.38
February 12: 0.62

February 14: 0.26

Total: 8.96"
( February 1-14 AM )

The monthly total at Big Cherry Dam has been 
approximately 10.17" through February 14.

February 14, 2018
The BEAUTY of The South Fork
Photograph by Wayne Browning - © All Rights Reserved

The affect of SW flow was on full display February 14, 
with intervals of hazy sunshine amid downslope breaks 
in northern Wise County and Dickenson County.

This boosted afternoon temps to 61 degrees in Clintwood to contrast with 40s to around 50 degrees at upper elevations in the High Knob Massif ( as well as in persistent fog zones, like Little Stone Mountain Gap, at lower elevations within the 
SW upslope flow corridor ).

Just after I took the photograph below a bank of dense fog rolled upward through South Fork Gorge, which was below the low cloud deck due to sinking air into the Gorge during part of February 14.

February 14, 2018
South Fork Gorge During A Break In Fog
Photograph by Wayne Browning - © All Rights Reserved

Really, Really HUGE Numbers

High Knob Landform - Upstream of Norris Lake
Roughly 36 Percent of the Clinch-Powell River Basin

My friend Andrew Greear, Superintendent of the City of Norton Water Plant, and I were talking about the amount of water which is actually generated during such a big event as just 
witnessed & endured ( suffered by many ).

*I have to thank Chris Michaels, of WCYB, 
for getting us thinking along these lines!

The High Knob Landform, or geologic Powell Valley Anticline of the Cumberland Overthrust Block, is the most dominate ( largest ) single landform feature in the Clinch-Powell River 
basins and comprises very roughly about 36 percent of this ecologically renowned portion 
of the larger Upper Tennessee Basin.

*I can determine the value specifically using ArcGIS, but just for these approximate calculations a rough-and-dirty use of Google Earth will be sufficient ( above ).

Since Norris Lake essentially captures all the water flowing out of the Clinch-Powell river basin, this is the perfect setting to generate some realistic numbers ( at least, to stimulate thinking ).

Norris Lake - The First And Largest TVA Lake

About Norris Lake - More History & Information

First, this will not be as neat as I would do on a UVA-Wise whiteboard, so bear with me and understand these are just the rough numbers.  This is really quite simple, but might seem a bit complex at first ( the most important aspect, and reason for this illustration, being the SIZE of numbers that will be generated by just a quick inspection of this event in addition to its most important stimulation of thought ).

Andrew did a quick check while we were talking and the inflow to Norris Lake was 72,410 cfs ( cubic feet per second ) during the PM of February 12.

A 1.00 cfs flow rate = 7.48 gallons per second

( 72,410 cfs )( 7.48 gal per second ) 
= 541,626.8 gallons per second

( 541,626.8 gallons per second )( 60 seconds per minute ) 
= 32,497,608 gallons per minute

 ( 32,497,608 gallons per minute )( 1440 minutes per day ) 
= 47 Billion gallons of water inflow per day 
at the current inflow of 72,410 cfs.

4.7 x 10^10 gallons of water per day

So roughly 47 Billion gallons of water entering Norris Lake per day at that particular inflow of 72,410 cfs.  Merely a moment in time.  

The above is just decoration.  Lets get
 to the real core of this particular event.

Norris Lake covers 33,840 acres

Lake level changes
1002.84 feet at 0200 hours on February 10
1012.63 feet at 1800 hours on February 12

Round to 10 vertical feet of lake level rise.

There are 325,853.4 gallons in an acre foot.

( 33,840 acres ) ( 10 feet ) = 330,840 acre feet

( 330,840 acre feet ) ( 325,853.4 gallons per acre foot )
= 1.08 x 10^11 gallons of water

108,000,000,000 Trillion 
gallons of water gained.

So what does that imply?

The Clinch-Powell river basins contain
 approximately 4,413 square miles, with around 
1.7 Million acres upstream of Norris Lake.

Clinch-Powell Clean River Initiative

( 1.7 million acres ) ( 1 square mile per 640 acres )
= 2656.25 square miles

A total of 2656 square miles within
the Clinch-Powell River Basins.

A 1" rain over 1 square mile produces an
approximate 17,378,743 gallons of water

( 17,378,743 gallons per square mile per 1" of rain )
multiplied by ( 2656.25 square miles )
= 4.6 x 10^10 gallons per 1" of rain

Roughly 46 Billion gallons of water is 
produced by every 1" of rain that falls 
upon the Clinch-Powell Basin.

From here is it easy to see that:

( 4.6 x 10^10 gallons per 1" ) ( 2.35" )
= 1.08 x 10^11 gallons

The 10 vertical feet of water level rise on Norris Lake, at the point in time this was calculated, implied that 2.35" of rain ran off ( on average ) 
from the Clinch-Powell River Basin.

If only 2.35" ran off, on average, why did it flood?

NWS Precipitation Estimated Past 7 Days
( February 5-12, 2018 )

Even though local estimates are too low, please observe that the regions of heaviest rainfall across the southern Appalachians are clearly those which received upsloping on SW air flow.  The High Knob Landform corridor and locations in southwestern North Carolina ( in this type of flow ). 

ALERT...ALERT...SW Flow is Upslope Flow
in favored regions of the Appalachians!!!!

In reality, more fell on average than calculations generated and certainly more also fell locally than the NWS Analysis ( above ) estimated ( due to a lack of input data from favored orographic forcing locations within far southwest Virginia especially ).

There are numerous reasons for this.

Not all water that falls runs off to reach the main lake, some goes subterranean, some evaporates, some is retained within wetlands and other water bodies and does not flow to the main water body, and during the growing season ( especially ) much undergoes uptake by trees and vegetation.

Another reason, that is very important, is input across the Clinch-Powell Basin was heterogeneous, highly non-uniform with the most significant input being injected by the minority 36% of the 
High Knob Landform corridor versus the remainder of the Clinch-Powell Basin.

*Even though the High Knob Landform is the largest single landform feature in this basin, it still comprises 
the minority of the total 2656 square miles.

What makes this more significant than in most cases is the fact ( as my climatology documents ) that average annual precipitation decreases UP-BASIN across the Clinch-Powell beyond the massif of High Knob instead of increasing as is more typical of most river basins.

**Annually, for example, there is a HUGE decrease in precipitation going from southwest to northeast from 
Big Cherry Dam to Burkes Garden ( even though both locations are essentially at the same elevation 
above mean sea level ).

Case in point, during the February 10-12 period a total of 1.60" of rain was officially measured near the head of the Clinch River in Burkes Garden versus 6.85" at approximately the same elevation in the High Chaparral-Robinson Knob communities of the High Knob Massif ( from a IFLOWS that has a well documented  history of reading lower than hand-measured gauges ).

At least a 5.25" difference ( decreasing up-basin ). 
If it were not for years of very well documented conditions this might be written off as merely an anomaly associated with this particular weather system; however, it is actually a persistent and strong factor in the long-term climatology of southwestern Virginia.

Reference The Wettest February On Record 
below for more details on this type of flow.

NOTE all elevations are NOT created equally as
there is more to annual wetness than mere elevation!

Finally, snow melt contribution can not be neglected as it added more water than modeling predicted, especially for locations downstream of the High Knob Massif where river level forecasts  had to be adjusted UPWARD the most during the course of this event.

Crazy But Awesome Rime
Upper Norton Reservoir of High Knob Massif
February 12, 2018

Rime In Curls
Becky Lagow Photograph

I have seen rime for decades, and some crazy stuff, but I have to sure thank my friend Becky Lagow for finding probably the most unique rime formations I have ever seen in the high country.

February 12, 2018
Unique Curls Of Rime
Upper Norton Reservoir of High Knob Massif
Photograph by Becky Lagow - © All Rights Reserved

This rime displays the characteristic INTO the wind growth pattern, and a layering seen so often with deposition over time, but otherwise has developed an epic form.

Deposition with transformation from supercooled cloud vapor to solid rime is an exothermic process that releases 680 calories of energy per gram of water into the air ( the combined energy from condensation + freezing ).

Well it might appear that the rime has merely formed on a vine, but in fact NOT!  There is no vine present!  The explanation is NOT for certain, but I feel it is definitely related to turbulent air flow and abundant low-level moisture present in wake of flooding rainfall that was subjected to a rapid temperature drop into early Monday amid orographic clouds.

Awesome Curls of Rime
Becky Lagow Photograph

A temperature gradient generated by a difference between water in the lake, that was warmed by heavy rain ( versus recent ice coverage ), and air surrounding the lake may have played a role in creating the swirling air motions necessary to generate this awesome rime.

The Wettest February On Record
( All-time Record For Virginia )

500 MB Height Anomalies - February 2003

Much like the current pattern, the main anomaly during February 2003 featured a SW upper air flow pattern across the eastern USA with a notable gradient between High Pressure in the western Atlantic and a cold trough over the central USA.

The all-time wettest February on local record, as well as for the state of Virginia, occurred during 2003 when the Big Stone Gap WWTP established a new all-time mark for wetness in the Old Dominion during February with 11.81" of total precipitation.

February 13-23, 2003
850 MB Vector Wind Anomalies

The period that generated excessive rainfall featured a mean SSW flow at 850 MB during 
the February 13-23 period in 2003.

Much like the current pattern, it was an hyper-active weather period that again featured huge rains and a melting high country snowpack 
( deeper than in 2013 ).

Notes From My Climate Archive

February 14-16, 2003
Major storm produced excessive rainfall and flooding!  Mudslides and high water problems became widespread as a major storm system dumped more rain within 72-hours than 
typically falls during an entire February!

The greatest valley rain total was measured by Jennifer 
and Tracy Garrison in the Cracker Neck community of 
Powell Valley, with 6.30" that barely topped the 6.28" 
measured at the Big Stone Gap WWTP.

Flooding from the City of Norton into river valleys of the Clinch and Powell would have been more severe had all the snow melted off the high country surrounding High Knob, above 3500 feet, where I measured north slope depths of 7" to 12" . 

A snow core found 2.00" to 4.00" of water locked in the 
snowpack in wake of this major rainfall event, and large 
decrease in snow depths.

Around 30.0" of snow fell at the summit level of
the High Knob Massif during February 2003, on the
way to between 90" and 130" at elevations above
3000 feet during the Winter Season of 2002-03 .

February 21-23, 2003
Second major storm hammers mountains!  The second major league storm system within less than a week hammered the area, with at least 100 roads being blocked by high water, mud, and rock slides by early afternoon of February 22 in southwest Virginia.

   A near major disaster was prevented only by a prolonged break in rainfall amid the windy, warm sector of the system which itself generated a line of severe thunderstorms packing high winds and pea to quarter size hail.

   Incredibly, a 1 to 3 inch blanket of snow fell upon the battered landscape a few hours after severe thunderstorms.

Precipitation Totals
February 2003


North Fork of Pound Lake

John Flannagan Lake


Clintwood WWTP

Breaks Interstate Park

Wise 3 E

Pennington Gap

Closplint, KY

Black Mountain, KY

Norton Water Plant

Appalachia Lake WP

Big Stone Gap WWTP

Cracker Neck of Powell Valley

Unofficial totals were locally greater, of course, with Jennifer & Tracy Garrison measuring 11.96" 
of total precipitation in the Cracker Neck of Powell Valley.  Totals over 12.00" occurred within upper elevations of the High Knob Massif.

State of Virginia - NCDC
Total Precipitation For February 2003
Central-Southwest Mountain Climate Zones

Although a ( M ) is in front of Burkes Garden, the final total 
reported by Mrs. Colleen Cox was 7.74" in Burkes Garden.

During the wettest February on record totals going up-basin in the Clinch from the High Knob Massif decreased from 11.00-12.00"+ within the massif area to the following:




Burkes Garden


*Bluefied FAA Airport

*Just adjacent to the basin head.