Sunday, February 28, 2010

February 2010 - Month of NW Flow Snowfall


February 2010
High Knob Massif - NW Flow Snowfall
Photograph by Roddy Addington - © All Rights Reserved.


February 2010 will be remembered as a month dominated by NW flow snowfall, with three major events being observed.

Elevation 3300 feet
High Chaparral - Light Snow & Capping Pilatus - Feb 23
Photograph by Darlene Fields - © All Rights Reserved.

This final event began as colder air returned into morning hours of February 23, with cloud bases lowering to obscure the High Knob highcountry within an icy, RIME generating fog.  Darlene Fields also captured a few flakes falling upon her still snow covered driveway ( southern exposure ). 

February 24, 2010
Remnant Massif of High Knob Landform
RIME & Light Snow - High Knob Massif
Photograph by Roddy Addington - © All Rights Reserved.

[ Snow depths of 10"-20"+ were still common across northern slopes and crestlines of the High Knob Massif, above 3000 feet, during February 24 ( with much less at lower elevations and in southern exposed locations ) ].

A truly gorgeous RIME event unfolded itself before the camera lens of Roddy Addington during afternoon hours of February 24, as snow began to increase amid the highcountry in advance of an arctic cold front.

Gorgeous RIME Setting
Layered RIME & Lichens - High Knob Massif
Photograph by Roddy Addington - © All Rights Reserved.

Layered rime on a tree heavily covered by lichens created an amazingly colorful winter scene in the snow laden highcountry. 

[ Note wind directions in the above photograph were from left to right, with RIME growing INTO the wind. Since this event had only been ongoing for 24-30 hours, at the time of this photo, the rime possessed a very feathery nature with new layers beginning to elongate adjacent to the original deposition of cloud vapor ( being especially notable along the trunk sprout )].

Jefferson National Forest
RIME Feathers on Trees - High Knob Massif
Photograph by Roddy Addington - © All Rights Reserved.

Like feathers plucked from a chicken, rime formed on tree trunks to create unusual designs.

Feathered Trees! 

Feathery Layers of Rime - Windward Side of Branches
Photograph by Roddy Addington - © All Rights Reserved.

The feathery nature of rime layers, formed on the windward side of tree branches, is very evident upon closer inspection ( with leeward or downwind sides remaining distinctly bare ).

February 24, 2010
Opposite Viewpoint - Layered Rime
Photograph by Roddy Addington - © All Rights Reserved.

Of special interest in the above photograph are points of contact of the rime on the tree branches.

Layered Riming On Hardened Weed
Photograph by Roddy Addington - © All Rights Reserved.

[ Riming during this event, amid light winds relative to those most often observed with High Knob Massif episodes, resulted in creation of a "softer" rime that was more feather-like outward from rather tenacious points of initial contact deposition ( the actual contact zone being marked by a bluish halo adjacent to branches in the previous photograph ) ].

High Knob Massif on February 24, 2010
Caution - EYE ALERT - Amazing RIME Pattern
Photograph by Roddy Addington - © All Rights Reserved.

Rime is essentially frozen clouds of water that have been extracted from the air ( the greatest extraction occurring via trees ).

Most often this occurs via trees and vegetation on High Knob, but it can occur on other upright objects like this chain-link fence!

[ Reference the following sections of my website to learn more about RIME and it's importance to the annual water budget of the sprawling High Knob Massif:

Main Rime Section
http://www.highknoblandform.com/2009/10/high-knob-massif-dazzles-in-first.html

Rime & Hoar Frost
http://www.highknoblandform.com/2009/12/early-december-winter-wonderland.html

Gorgeous Rime Landscape Photographs
http://www.highknoblandform.com/2010/02/majesty-of-endless-winter-in-hkl.html

More Gorgeous RIME Landscapes
http://www.highknoblandform.com/2010/03/march-2010-intro-big-show-part-one.html

Example of "Hard" Rime in High Winds
http://www.highknoblandform.com/2010/01/belated-christmas-present-winter-beauty.html  ].

High Knob Massif
Rime Coated Vine - February 24, 2010
Photograph by Roddy Addington - © All Rights Reserved.

Although large trees collect the most rime, due to their big surface areas, it will coat any above ground object ( even you ) if it stands amid sub-freezing cloud vapor long enough ( covering them, as illustrated, with absolute precision along their windward sides ).

[ The above making RIME a major secondary moisture source to the annual water budget of the High Knob Massif ]. 

February 24, 2010
Shape Does Not Matter - RIME Conforms
Photograph by Roddy Addington - © All Rights Reserved.

RIME is truly magical in that shapes simply do not matter, it will conform and swirl itself into any possible configuration to often generate designs in nature which are unbelievable ( it is, after all, a product of very tiny water vapor droplets ).

High Knob Massif
Northern Red Oak ( Quercus rubra var. borealis
Photograph by Roddy Addington - © All Rights Reserved.

After a winter like 2009-10 it is hard enough to believe that a few Northern Red Oak leaves could hang on trees amid the highcountry, let alone that they would be sporting rime swirls like Roddy first illustrated way back in October 2009 ( having endured so many brutal, winter storms )!

February 24, 2010
TOUGH Leaves - High Knob Massif 
Photograph by Roddy Addington - © All Rights Reserved.

How could a "Mini-Me" leaf piece, dangling below, survive to even sport RIME too?

Even A "Mini-Me" Leaf Swirl
Photograph by Roddy Addington - © All Rights Reserved.

[ The NW flow events of February 9-11 and February 15-18 both generated a bounty of riming across upper elevations within the great High Knob Massif, and along higher mountain rims of its extended landform ( such as the backbone of magnificent Cumberland Gap National Historical Park ) ].

This final NW flow event of February has been the most strange locally, with a push of upslope snow showers and squalls during February 24-25, following highcountry riming, on the fringe of a large New England Nor'easter.

Much of the event actually being driven by spokes of energy rotating around the far away Nor'easter, instead of cold air advection and Great Lake moisture on pure NW upslope flow into the southern Appalachians ( thus, there were several atypical breaks during the course of this prolonged episode ) ].

February 25, 2010
NW Flow Snow Showers & Squalls - Long Ridge
Photograph by Wayne Riner - © All Rights Reserved.

Increasing winds caused drifting to develop across the highlands, as Wayne & Genevie Riner reported that snowfall came in waves during the day ( upslope snow showers & squalls forming and reforming in typical NW flow fashion ).

February 25, 2010
Drifts on Long Ridge of the Tennessee Valley Divide
 Photograph by Wayne Riner - © All Rights Reserved.

A total of 5.2" of snowfall were measured on Long Ridge into morning hours of February 26, with gusty winds creating variable ground depths.

Gusty Winds & Snow Showers - Long Ridge - Feb 25 PM
Photograph by Wayne Riner - © All Rights Reserved.

Darlene Fields measured 8.0" of new snow in High Chaparral of the High Knob highcountry into morning hours of February 26, with locally 10-12" of new falling amid highest elevations from the massif into adjacent Big Black Mountain. 

February 26, 2010
Glorious Sunrise Above High Knob Massif
Photograph by Roddy Addington - © All Rights Reserved.

A break in the NW upslope event was then announced in glorious fashion by a magnificent sunrise over the High Knob peak ( the first of several atypical breaks during this event ).

[ The edge of the actual peak of High Knob is just barely visible through Rocky Hollow Gap in the above photo
( look at gap in high crestline ).

The peak of High Knob stands 402 vertical feet above the highest portion visible of Grindstone Ridge Dome ( 3821 feet ) which, according to my friend Addison Stallard, was once known as the Rich Butte ( also visible in this beautiful photograph below ) ].

PM of February 26, 2010
Gorgeous Grindstone Ridge Dome
High Knob Massif Above Powell Valley
Photograph by Roddy Addington - © All Rights Reserved.

Rod Addington Photography

A striking contrast was created into afternoon hours of February 26, as clouds cast dark shadows upon the highcountry above Powell Valley.  Deep snow, along and above dramatic lines of calcareous cliffs, blue skies, and golden brown Valley fields added to this spectacular setting!

[ The sprawling expanse of the High Knob highcountry, including the peaks of High Knob, Eagle Knob, Little Mountain Knob, Camp Rock, and numerous others, are not visible in such a view to hide the fact that a great massif spreads outward for miles beyond the Valley floor! ].


Lee County Excursion

During this break an excursion into Lee County, Va., will be a nice way to spend our time ( look for a complete recap of February and snowfall event tallies at the end of this update ).

Williams Mill - Lee County of HKL - February 2010
Photograph by Harold Jerrell - © All Rights Reserved.

Although receiving only a fraction of the snowfall of the High Knob highcountry during February, as will be later highlighted by some impressive numbers, the grand HKL landscape southwest of its remnant massif in Lee County, Va., is always beautiful.

Williams Mill & Pond - Lee County
Photograph by Harold Jerrell - © All Rights Reserved.

Its special beauty arises from an interesting mixture of history, culture, and great ecological richness amid the calcareous heart of this ancient mountain landform.

Williams House Square - February 2010
Photograph by Harold Jerrell - © All Rights Reserved.

Beautiful Williams Creek
Photograph by Harold Jerrell - © All Rights Reserved.

The great Stone Face is a well known landmark in the Pennington Gap area.

The Great Stone Face - NW Arm of HKL
Photograph by Harold Jerrell - © All Rights Reserved.

It formed within a highly resistant Middle Lee Formation quartz arenite sandstone unit of Lower Pennsylvanian age stratigraphy, and is exposed within the "Pennington Gap" which breaches the northwestern arm of the High Knob Landform.

[ Quartz arenite sandstones uphold much of the northwestern arm of the HKL, as well as extensive portions of the highcountry of its remnant massif ].

Cumberland Gap Church - Feb 2010
Photograph by Harold Jerrell - © All Rights Reserved.

February snow paints a lovely picture at the next breach within the northwestern arm of the High Knob Landform, more than 30 air miles to the southwest, amid famous Cumberland Gap.

Near Hagan & Poor Valley Ridge Gap of HKL
Photograph by Harold Jerrell - © All Rights Reserved.

Interior ridges within the HKL, between its main mountain flanks and remnant massif, are upheld by more resistant rock stratas than those composing valley floors, but much less extensive and competent layers than its lofty highlands. 

[ Examples being Wallen Ridge, Poor Valley Ridge, and minor rises like Skeens Ridge in Powell Valley of Wise County ].

Gibson Station Area of HKL - Western Lee County
Photograph by Harold Jerrell - © All Rights Reserved.

Poor Valley Ridge can be traced through most of Lee County, rising along the southeastern base of the much higher and prominent Cumberland-Stone Mountain arm of the High Knob Landform 
( the NW forelimb of the geological Powell Valley Anticline of the Cumberland Overthrust Block ).

[ Poor Valley Ridge is upheld by a weakened form of Clinch Sandstone due to a major facies change in deposition, between Wallen Ridge, Powell Mountain, and Clinch Mountain, from a beach onshore setting to a deeper marine setting.  This softer sandstone of Poor Valley Ridge has allowed it to be weathered faster, resulting today in a low running and occasionally broken ridge from Lee County into northern Tennessee ].

Natural World Unites In HKL
Photograph by Harold Jerrell - © All Rights Reserved.

An intimate, inseparable union of climate with geology over time has generated incredible surface and subterranean topography, and vast biodiversity, of the great High Knob Landform 
( and is the reason for this website ).


February Snowfall Totals

February 28, 2010
Deep Snowpack & Drifts - High Knob Massif
Photograph by Roddy Addington - © All Rights Reserved.

February 2010 snow totals of 40-60" were common across the High Knob Massif, above 3000 feet, with specific amounts including:

High Chaparral: 44.0"
Eagle Knob: 56.0"

February 28, 2010
Gorgeous RIME Designs - High Knob Massif
Photograph by Roddy Addington - © All Rights Reserved.

[ The greatest February's of the past several decades have generated 3.5 to 4 feet of snowfall in the High Knob Massif during:

February 1985
February 1996
February 2006

The above information courtesy of Carl Henderson, Dennis Salyer, Terry Surface, Joe & Darlene Fields, Otis & Nancy Ward, Steve Blankenbecler, and Wayne Browning ].

Exotic Shot - Norton Reservoir - High Knob Massif
Photograph by Roddy Addington - © All Rights Reserved.

Most of the snowfall during February 2010 came via northwesterly wind trajectories, with the following main events being observed.

NW Flow Event Totals

February 9-11: 14-18"

February 15-18: 16-20"

February 24-28: 8-12"

February snowfall totals across the High Knob highcountry were rather impressive, especially given that 2 significant snow events were largely missed during the month.

February 28, 2010
Benges Basin of Powell River Basin
Intricate Glaze-Rime Pattern - High Knob Massif
Photograph by Roddy Addington - © All Rights Reserved.

[ A combination of glazing and riming formed an incredibly intricate pattern on evergreen trees within lofty Benges Basin of the High Knob Massif into February 28, as captured above by Roddy Addington ].

Growing Jewels - High Knob Massif Rime & Ice
Photograph by Roddy Addington - © All Rights Reserved.

The major February 5-6 cyclone generated an ice storm across the highcountry, with only 2-3" of new snow.

[ Reference this section of my website for details on the Ice Storm:

The final NW flow event, during February 24-28, was also largely a miss given the local mountains were only on the outer fringe of the massive storm circulation ( with the event driven by wrap-around snowfall, more than by cold advection with Great Lake moisture transport on pure upslope flow ).

February 28, 2010
Awesome Photograph
Feathery RIME In High Knob Massif
Photograph by Roddy Addington - © All Rights Reserved.

[ Gorgeous, incredible RIME formations developed once again amid abundant low-level moisture being lifted across windward slopes of the High Knob highcountry on Feb 27-28 ].

February 28, 2010
RIME Feathers - High Knob Massif
Photograph by Roddy Addington - © All Rights Reserved.

The February 24-28 event generated multiple episodes of incredible riming within the High Knob Massif, as illustrated by these awesome Roddy Addington photographs ( riming continued into March 2010 ).

Hard Rime In Stronger Wind Exposure
Photograph by Roddy Addington - © All Rights Reserved.

[ In locations exposed to strong winds a "harder" form of RIME developed, as illustrated by Roddy above, which is distinctly different in nature from the feathery rime deposition within places protected from roaring winds ].

More Rime Feathers - High Knob Massif - Feb 28
Photograph by Roddy Addington - © All Rights Reserved.

Snow depths during the month peaked amid the Feb 15-18 event, with a general 16-24" on southern slopes and 30-40" on northern slopes ( above 3000 feet ).  These depths rivaled those observed during the great Mega-Disaster Dump event of December 18-19, 2009 ( when they accumulated in less than 24-hours by a unique circulation ).

[ For details of this disastrous event, and MEGA-dump in the High Knob highcountry, please reference the following section of my website:


The above totals are especially impressive when considering those reported within the Great Valley of Tennessee, from the Tri-Cities to Knoxville, where downsloping tends to be a major factor during NW flow events.

February 2010 Snowfall Totals
( Great Valley of Eastern Tennessee )

Tri-Cities: 6.3"
Knoxville: Trace

[ These February totals are rather hard to believe, but are      the official tallies reported for these locations. Unofficial snowfall amounts of 4-14" are noted within the Kingsport-Gray, Tn., area for February 2010 ].

February 28, 2010
Winter GEMS - High Knob Massif
Photograph by Roddy Addington - © All Rights Reserved.

[ Like a secret stash of exotic gems, amid all the deep snow, Roddy managed to discover this absolutely beautiful scene ( but he'll never tell where it's hidden! ) ].

Since February is a short month, snowfall totals during the 31-day period from Jan 29 to Feb 28 reached 54" in High Chaparral and approximately 69" on Eagle Knob ( more than ever measured during an entire winter in the Tri-Cities, TN ).

[ The greatest 30-day snowfall total on record within the High Knob Massif, since late 1980s, reached 80-90" ( approximately 83" on Eagle Knob ) during the Feb 13-Mar 14 period of 1993 ].

High Knob Massif RIME - February 28, 2010
Photograph by Roddy Addington - © All Rights Reserved.

However, the fact remains that more February snow still fell at highest elevations within the High Knob highcountry than has ever officially been measured in the Tri-Cities during an entire winter ( TRI record: 51.1" during 1959-60 season ).

February 28, 2010
Developing Rime Feathers - High Knob Massif
Photograph by Roddy Addington - © All Rights Reserved.

Rime, Leaves & Lichens - High Knob Massif
Photograph by Roddy Addington - © All Rights Reserved.


February Coldness

 Majestic Bark Camp Lake - February 28, 2010
Photograph by Roddy Addington - © All Rights Reserved.

[ Looking across toward the northern side of Bark Camp Lake, sitting at 2734 feet above sea level amid Little Stony Basin of the High Knob Massif, one can see that snow is much deeper on top of thicker ice covering the shadier, colder northern shoreline ].

Coldness ruled the month of February with only a four day thaw, during Feb 19-23, which generated much above average temperatures.

Elevation 2734 feet
Little Stony Basin of the Clinch River Basin
Frozen & Cold - Bark Camp Lake - High Knob Massif
Photograph by Roddy Addington - © All Rights Reserved.

A mean February temperature of 26.0 degrees was recorded in the city of Norton, with daily mean variations of 33.8 and 18.3 degrees, respectively ( in degrees Fahrenheit ).

February 28, 2010
Bark Camp Lake - High Knob Massif
Photograph by Roddy Addington - © All Rights Reserved.

Lofty mid-upper elevation basins within the sprawling High Knob Massif, possessing valley floors between 2400 and 3600 feet above sea level, had diurnal extremes varying from the 20s by day to low-mid 10s by night.

February 28, 2010
Frozen In Time - High Knob Massif
Photograph by Roddy Addington - © All Rights Reserved.

Despite persistent coldness, no truly extreme days have occurred this winter where temperatures remained sub-zero by both night and day 
( a most interesting fact! ).

February 28, 2010
Second Half Of A Harsh Winter Season
Bark Camp Lake Ripples & Ice - High Knob Massif
Photograph by Roddy Addington - © All Rights Reserved.


Dreams of Spring!

Song Sparrow ( Melospiza melodia )
Photograph by Wayne Riner - © All Rights Reserved.

Wayne Riner Photograph Thoughts...
"The little bird has spent the entire year with us.  It nested in a bush near the garden and sat on the high post and sung its long song. It worked the garden rows as if it was "his" garden. Now sitting in the cherry tree, with the snow and wind, spring seeming only a dream!"

Despite all the absolutely GLORIOUS & MAGNIFICENT winter photography highlighted since mid-October 2009 on my High Knob Landform website, there is a given time and place for everything.  Now, at the dawn of March, and the beginning of Meteorological Spring, hopes rise in the wake of a long, harsh winter that a new season of rebirth & renewal will finally arrive!

Spring Dreams - Wishing For The Season
Photograph by Harold Jerrell - © All Rights Reserved.

As more cold & snow open March 2010 only spring dreams are alive that such scenes as above will soon come to cover the great High Knob Landform and southern Appalachians!

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