Tuesday, March 24, 2015

Wet March 2015 & Virginia Precip Differences


March 9, 2015 at 6:08 PM
Head of High Knob Lake Basin
Northern Slopes of High Knob Massif
General 10-15" of Snow Depth Following Flooding
Photograph by Wayne Browning - © All Rights Reserved.

Water from heavy rain running down trees had melted rings around tree bases throughout the northern woods, which had been wind blasted with many tiny fragments visible in the snowpack from strong wind speeds of recent days.




A general 10" to 15" of snow depth, with 18" to 30" in places, remained across northern exposed slopes of the High Knob Massif in wake of extensive flooding during the first week of March 2015.

High Knob Massif
March 9, 2015 at 7:18 PM
Head of Big Cherry Lake Basin
Walking On Top Of 30" Of Snow Depth
Photograph by Wayne Browning - © All Rights Reserved.

This was a true snowpack with bottom snow from January 2015 lingering amid the high country of this great massif.  Snow was packed so hard that I could walk on top of up to 30" of depth without breaking through, at least in places.

*A most impressive feat given 4.00" to 5.00" of precipitation 
( largely rain ) during March 1-6 and loss of up to 30" or more of total snow depth.

The snow depth loss by afternoon of March 9, from near MAX depths reached late on February 21 into February 22, can be illustrated by these images from Eagle Knob.

February 21, 2015 at 9:05 PM
Eagle Knob of High Knob Massif
Image by Cody Blankenbecler - © All Rights Reserved.

These images from my friend Cody Blankenbecler illustrate how much snow had already disappeared on Eagle Knob by the time I measured snow depths during March 9 ( around 30" of depth had melted at snow markers on Eagle Knob ).  Note how depths change along the chain-link fence by clicking back and forth in the picture viewer.

March 9, 2015 at 4:12 PM
Eagle Knob of High Knob Massif
Image by Cody Blankenbecler - © All Rights Reserved.

A snow core taken on 11" of depth produced 5.20" of water content on March 9, with general 4.73" to 7.09" of water contained in the general snowpack 
( locally much more in deep areas ).

March 9, 2015 at 6:48 PM
State Route 619 Visible In Distance
Deep Snow Across High Knob Lake Basin
Photograph by Wayne Browning - © All Rights Reserved.

This was a tenacious snowpack and one of the most difficult to fully melt away that I had seen in years, likely due to its layered development over time and high water content.


A generalized snowpack profile from the end of February, that I made of the snowpack in Clintwood, was applicable to the deeper, wetter snow in the High Knob Massif.

High Knob Lake Basin
March 9, 2015 at 6:01 PM
Looking North Toward The High Knob Lookout
Photograph by Wayne Browning - © All Rights Reserved.

The widespread nature of the snowpack left on March 9 was clearly visible from the new High Knob Lookout Tower.

March 9, 2015 at 6:47 PM
Looking Southeast From High Knob Lookout
Photograph by Wayne Browning - © All Rights Reserved.

The ice covered surface of High Knob Lake is partially visible near center of the above photograph, with a small section of ice covered Big Cherry Lake shown in a picture below.

March 9, 2015 at 6:45 PM
Looking Southwest From High Knob Lookout
Photograph by Wayne Browning - © All Rights Reserved.

March 9 was amid the great melt down period with high water volume on steep creeks draining the massif for days following this time as snow melted slowly ( thankfully ) and more rain fell to push creeks to near or locally above flood stage again.

The NWS Forecast Office In Morristown, Tn., made the wrong call by not issuing a flood watch for all this snow melt, with water around homes in the Tacoma area and in other places along creeks draining the massif during March 10-11.  A flood watch was properly issued in advance for the significant flooding observed during early March, which was an excellent call by the MRX NWSFO.

*If creeks do not need watching then a Flood Watch or Flash Flood Watch is not needed.  If creeks need to be watched by residents, then clearly a watch is needed.  In this case, there was no question that creeks needed to be closely watched in Wise, northern Scott & Lee counties.

March 9, 2015 at 6:47 PM
Lookout SW Across High Country
Small Portion of Ice Covered Big Cherry Lake
Photograph by Wayne Browning - © All Rights Reserved.

Main-stem rivers remained well below flood stage during this secondary run-off period when it was headwater creeks that rose to within a foot or less of flood stage.

March 10-12, 2015
Big Stony Creek Stream Levels
Big Stony Creek was 11" below flood stage
at the stream gauge point recorded above

When levels on steep creeks draining the massif reach those shown above they ROAR and are so loud that you can not hear somebody talking standing right beside you.

It is a very powerful experience to witness and I encourage anyone who has not observed these creeks, at or above the "Red Alert" level, to do so.

A few of the creeks I'm talking about include:

Big Stony Creek
Burns Creek
Chimney Rock Fork
Clear Creek
Cove Creek
Devils Fork
Laurel Fork
Little Stony Creek
Machine Creek
Roaring Branch
Straight Fork
Stock Creek
South Fork of the Powell
Guest River Gorge

There are many more creeks.  While most do not have a stream gauge like Big Stony Creek, it can be used as a general guide for the other steep creeks, especially during the cold season.

During summer the possibility of localized downpours in thunderstorms can cause large flow volume differences between adjacent creek basins.

The High Knob Massif is unique in that most major creeks are lake and/or wetland controlled to some extent, with locally significant subterranean conduits retaining much more water.

High Knob Lake holds back water into 
Big Stony Creek of the Clinch River

Big Cherry Lake holds back water 
into South Fork of the Powell River

Bark Camp Lake holds back water into 
Little Stony Creek of the Clinch River

Dual Norton Reservoirs hold back water into 
Benges Branch & City of Norton that feed into 
the Middle Fork of the Powell River

The Glades wetlands slow water going 
into Big Stony Creek and the Clinch River

Appalachia Lake and Keokee Lake along the
Little Stone Mountain-Stone Mountain flank hold back
water entering Middle & North forks of the Powell River

The longest cave system in Virginia, and deepest east of
the Rockies & north of Mexico in North America helps to
hold back and slow run-off until the conduit system fills

*The above being examples, with more ponds-wetlands and
many cave systems that are part of a complex hydrology.

Any area will flood, and certainly that was the case during early March when heavy rain combined with significant loss of snow to generate extensive flooding, rock-mud slides in the area.


March 5, 2015
Clinch River Near Speers Ferry In Scott County
Photograph by Roddy Addington - © All Rights Reserved.

It was a great blessing that deep snow remained and did not all melt away during the early March flooding or it would have been much worse across Wise, Scott, Lee counties.


More than 65 roads were closed in Wise, Scott, Lee, and Dickenson counties during early March.


Flooding of low-lying areas in the East Stone Gap-Big Stone Gap area typically begins when the river stage reaches 5.0 to 6.0 feet, with water around many homes during this early March episode.

March 4, 2015 at 8:27 AM
Run-off From High Knob Massif
Photograph by Cody Blankenbecler - © All Rights Reserved.

The photograph above was taken by Cody near the Flag Rock level, with the scene below at the base of the massif near the City of Norton Water Plant.

March 4, 2015 at 8:32 AM
Run-off From High Knob Massif
Photograph by Cody Blankenbecler - © All Rights Reserved.

The City of Norton rests upon a divide with water shown above flowing into the Powell River while water flowing off the massif east of Benges Branch, and the Norton Reservoir system, goes into the Guest River of the Clinch River.


With exception of January 2015, its been a wet orographic forcing season in the High Knob Massif area with abundant precipitation.

Big Cherry Lake Dam
Orographic Forcing Season
Monthly Precipitation Totals
Observers: Gary Hampton & Staff
Elevation 3120 feet

2014

October: 9.40"

November: 4.02"

December: 5.54"

2015

January: 2.87"

*February: 8.07"

March 1-16: 6.85"

January 1-March 16 Total: 17.79"

October 1-March 16 Total: 36.75"

Average Per Month: 6.66"

*The February 2015 total was mostly based upon 
snow core data and reported snow depths, with bulk 
of precipitation falling as snow above 3000 feet.

March 2015
Looking SW Across Big Cherry Lake Basin
Photograph by Wayne Browning - © All Rights Reserved.

Reference this link for details:
The Harsh Winter Month Of February 2015


Extraordinary Differences
In Southwestern Virginia Precipitation

Although I knew the High Knob Massif area had gotten the most snow in Virginia, as is common, even I was somewhat surprised upon recently catching up with climate data that anomalous dryness had been ruling locations to the east in southwestern and central Virginia.


Highlighting some of these extraordinary precipitation differences across southwestern Virginia ( and the state in general ) is one of the reasons I started this website back in Summer 2009, since most folks ( public & professional ) were not aware of these differences which are climatologically common.

Virginia Drought Monitor For March 3, 2015

There was some flooding in Wise County during February 21-22 with stopped up storm drains and so much snow that water could not run off roads.

Virginia Drought Monitor For February 24, 2015


Specific Site Comparisons

Danville
January 1-March 18: 5.33"
October 1-March 18: 14.85"
( 9.8" of total snowfall for season )

Roanoke
January 1-March 18: 6.41"
October 1-March 18: 16.03"
( 21.7" of total snowfall for season )

Blacksburg
January 1-March 18: 6.55"
October 1-March 18: 16.28"
( 27.8" of total snowfall for season )

Covington Filter Plant
January 1-March 18: 7.35"
October 1-March 18: 16.75"

Wytheville 1 S
January 1-March 18: 6.01"
October 1-March 18: 17.79"
( 20.2" of total snowfall for season )

Bluefield, West Virginia
January 1-March 18: 7.73"
October 1-March 18: 17.95"
( 39.5" of total snowfall for season )

Tri-Cities, Tennessee
January 1-March 18: 8.55"
October 1-March 18: 20.22"
( 15.5" of total snowfall for season )

Saltville 1 N
January 1-March 18: 8.27"
October 1-March 18: 22.16"

Grundy
January 1-March 18: 11.13"
October 1-March 18: 22.36"

Clintwood 1 W
January 1-March 18: 11.64"
October 1-March 18: 22.42"
( 41.6" of total snowfall during season )

Burkes Garden
January 1-March 18: 8.84"
October 1-March 18: 23.46"
( 41.0" of total snowfall during season )

Lebanon
January 1-March 18: 10.72"
October 1-March 18: 25.82"

Big Stone Gap WP
January 1-March 18: 13.62"
October 1-March 18: 31.69"

Appalachia Lake WP
January 1-March 18: 14.75"
October 1-March 18: 31.70"

City of Norton WP
January 1-March 18: 15.33"
October 1-March 18: 32.56"
( Around 60.0" of total snowfall for season )

Big Cherry Dam
January 1-March 18: 17.79"
October 1-March 18: 36.75"
( 120.0" of total snowfall in head of basin )

*Big Cherry Dam has missing data due to evaporation between hand-measurements which average 1 per week, and losses due to winter snowfall ( the February total being based upon snow core data ).

March 9, 2015
In High Knob Lake Basin
Looking North To High Knob Lookout
Photograph by Wayne Browning - © All Rights Reserved.

As in a previous photograph above, note the Lookout Tower
on the crestline amid upper left of photograph in far distance.


From Thunderstorms To Snow
Early Spring In The High Knob Massif
March 26-28 Weather Event

March 26, 2015 at 3:13 PM
 Looking Toward High Knob Massif
University Of Virginia's College At Wise
Billowing Clouds Develop Into Thunderstorms
Courtesy Of Computer Science-Mathematics Department

If you are a lover of extreme weather changes then the High Knob Massif was the place for you during March 26, with billowing clouds that gave way to downpours in thunderstorms followed by a change to wind driven snow ( within several hours! ).

March 27, 2015 at 1:48 AM
Heavy Snow On Eagle Knob of High Knob Massif
Photograph by Cody Blankenbecler - © All Rights Reserved.

Around 3" or more of snow accumulated at the summit level by morning hours of March 27 ( 0.32" of water release on Eagle Knob ), with sticking from around the Norton Reservoirs upward in elevation.

March 28, 2015 at 8:26 AM
 Looking Toward High Knob Massif
University Of Virginia's College At Wise
Courtesy Of Computer Science-Mathematics Department

Additional snow showers, flurries, and bursts of snow coated the mountain landscape into morning hours of March 28 as air temperatures plunged to around 10 degrees atop the High Knob Massif 
( with wind chills to -10 below zero in gusts ).

*Storm event precipitation totals ( water equivalent ) reached 1.50" at the City of Norton Water Plant, with 1.92" reported at the Lower Norton Reservoir.

This pushed the March 2015 precipitation total to 8.39" at the City of Norton WP ( 17.18" in 2015 ), with a general 8.00" to 10.00" of March precip amid the High Knob Massif area.

*City of Norton precipitation is hand-measured daily using an
official 8"-diameter National Weather Service rain gauge.

Latest USA Drought Monitor Graphic