Sunday, February 17, 2013

Winter Majesty of Mid-February Cold Blast


February 16, 2013
High Knob Massif Crest Zone
Majestic Rime Glows In Afternoon Sunlight 
Photograph by Roddy Addington - © All Rights Reserved.

The High Knob Landform

Written by Wayne Browning - October 2009...
"RIME makes the sprawling high country expanse of High Knob a water capturing wonder during the cold season, as moist, bitter winds are lifted and forced to rise, cool, and condense out their loads 
of moisture across its many lofty ridges & basins."

Introduction To RIME - October 2009 Dazzle Event

February 16, 2013
Windward Slopes of High Knob Massif
Darkening Skies Against Rime Forest
Photograph by Roddy Addington - © All Rights Reserved.

Rod Addington Photography

Low clouds lifted and parted just in time for photographers Roddy Addington and Bill Harris 
to capture an array of gorgeous scenes 
( as VDOT worked slick roads ).

High Knob Massif - Afternoon of February 16
Working State Route 619 In A Rime Forest
Photograph by Roddy Addington - © All Rights Reserved.

Wondrous windward growth of rime 
never fails to amaze!

February 16, 2013
High Knob Massif Crest Zone
Rime On Windward Side of Branches
Photograph by Bill Harris - © All Rights Reserved.

Temporary breaks formed in the overcast.

February 16, 2013 at 12:47 PM
Breaks Develop Above The Rime Forest
Photograph by Bill Harris - © All Rights Reserved.

When the summit was reached, by luck of timing, rime was stunning against an interval of blue skies as the heavens aloft turned increasingly bitter to indicate clearing would be short-lived.

Temperatures aloft were plunging during afternoon hours of February 16, with 40 to 50 below zero air poised to pass overhead ( above 17,000 feet ) by early evening.

February 16, 2013
Stunning Beauty of Rime On High Knob Peak
Photograph by Bill Harris - © All Rights Reserved.

There is much more to this stunning scene 
than meets the eye.

February 16, 2013
Below High Knob Meadow
More To This Scene Than Just Eye Candy
Photograph by Bill Harris - © All Rights Reserved.

Upon close inspection flakes of rime, 
much like snow, are throughout the air.

February 16, 2013
Rime On The Trees & In The Air
Photograph by Bill Harris - © All Rights Reserved.

This can be clearly seen by zooming 
in on Bill's high resolution photograph.

February 16, 2013
Rime Flakes Fill The Air On High Knob
Photograph by Bill Harris - © All Rights Reserved.

Many years ago I first got weather reports that it was snowing on High Knob out of clear skies!  In most cases this would be due to rime flaking off trees and swirling through the air like snow.

High Knob Massif
Flakes Filling The Air Amid Blue Skies
Photograph by Bill Harris - © All Rights Reserved.

In other cases, amid very cold air, ice crystals sometimes called Diamond Dust can fall out of cloudless air and glitter in sun or moon light.  

In the High Knob Massif this typically occurs as cold air that is relatively moist in surrounding valleys rises upslope where crystals form 
( sometimes with clear skies above ).

February 16, 2013
Looking Up Toward High Knob Meadow
Photograph by Bill Harris - © All Rights Reserved.

The MAX temp reached only 20 degrees on High Knob February 16 before bursts of afternoon snow developed beneath very cold air aloft.  A ferocious wind driven snow band later struck amid NW upslope flow into the overnight of February 17 ( highlighted later ).

Bill Captures The Motion Of Rime Flakes
Rime Flakes Falling In Mostly Clear Sky
Photograph by Bill Harris - © All Rights Reserved.

Although rime grows into the wind in saturated, sub-freezing air, the nature of this deposition as captured by Roddy shows how amid some bright sunlight ( insolation ) it might flake off into the blowing wind.

February 16, 2013
High Knob Massif Crest Zone
Close Up Of Rime Deposition On A Tree Limb
Photograph by Roddy Addington - © All Rights Reserved.


Recent Links of Interest

Cold & Snowy Opening To February 2013

The Fast & Furious Storm of January 2013



Caught In The Middle
But Still Wintry & Cold Enough

February 17, 2013
Chicken In The Snow On Sunday Morning
Photograph by Wayne Riner - © All Rights Reserved.

Wayne Riner Photograph Thoughts...
"The cement hen and family have seen many different weather patterns.  Sunday morning brought 11 degrees and snow."

Although caught in the middle, north and west of the best upper air support and south of the best Great Lake moisture, the High Knob Massif - Tennessee Valley Divide area still managed to collect a general 2" to 5" during this event.

A general 8" to 10" of snow was reported at the summit levels
of Mount Mitchell and Mount LeConte as the main upper air disturbance passed over the southern Appalachians on its way to produce rare Piedmont snow from Charlotte to Raleigh in North Carolina and support another Atlantic bombogenesis event.

This event came in three phases.

1 ).  A light lower elevation rain and upper elevation snow during February 15, with 0.5" to 1.5" above 3000 feet in the High Knob Massif and at lower elevations to the east-northeast.

Beginning of Rime Event
February 15, 2013 at 11:01 PM
Eagle Knob of High Knob Massif
Image by Steve Blankenbecler - © All Rights Reserved.

2 ).  A pocket of super-cold air aloft that triggered hit-miss snow showers and squalls during the afternoon of February 16, with best accumulations at mid-upper elevations where the air was more moist ( dry air hindered snow at low elevations ).

This setting was analogous to a summer shower pattern with a vertical temp drop from around 32 degrees at low elevations ( around 1500 feet ) to -40 to -50 below zero above 17,000 feet.  This steep lapse rate generated hit-miss downpours of snow with localized whiteouts for brief intervals amid the heaviest squalls.

NASA Visible Imagery Of Cold Air Aloft
Early Afternoon Development - February 16, 2013

Click consecutively on images for motion

NASA Visible At 11:02 AM - February 16, 2013

NASA Visible At 11:32 AM - February 16, 2013

Observe the formation of billowing clouds that grew vertically upward through the bitter air aloft, forming distinct cellular convective blobs indicative of steep lapse rates ( i.e., strong temp drops with height ).

NASA Visible At 12:02 PM - February 16, 2013

NASA Visible At 12:32 PM - February 16, 2013

NASA Visible At 12:45 PM - February 16, 2013

NASA Visible At 1:45 PM - February 16, 2013

NASA Visible At 2:02 PM - February 16, 2013

NASA Visible At 2:15 PM - February 16, 2013



Doppler Radar Patterns
Hit-Miss Snow Showers & Squalls
Afternoon-Early Evening of February 16, 2013

Click consecutively on images for motion

Doppler Radar Base Reflectivity At 4:00 PM

Doppler Radar Base Reflectivity At 4:10 PM

Doppler Radar Base Reflectivity At 4:19 PM

Doppler Radar Base Reflectivity At 4:29 PM

Doppler Radar Base Reflectivity At 4:39 PM

Doppler Radar Base Reflectivity At 4:49 PM

Doppler Radar Base Reflectivity At 4:59 PM

Doppler Radar Base Reflectivity At 5:08 PM

Doppler Radar Base Reflectivity At 5:18 PM

Doppler Radar Base Reflectivity At 5:27 PM

Doppler Radar Base Reflectivity At 5:40 PM

Doppler Radar Base Reflectivity At 5:49 PM

Doppler Radar Base Reflectivity At 5:59 PM

Doppler Radar Base Reflectivity At 6:09 PM

Doppler Radar Base Reflectivity At 6:19 PM

Doppler Radar Base Reflectivity At 6:28 PM

Doppler Radar Base Reflectivity At 6:38 PM

Doppler Radar Base Reflectivity At 6:48 PM

Doppler Radar Base Reflectivity At 6:57 PM

Doppler Radar Base Reflectivity At 7:07 PM

Doppler Radar Base Reflectivity At 7:17 PM


3 ).  The third and final phase of this event featured a surge of bitter air and some NW upslope flow bands of snow during the overnight hours of February 17 ( with hazardous driving conditions ).


Snowstreaks With Heavy Snow
February 17, 2013

Click consecutively on images for motion

Doppler Radar Base Reflectivity At 12:07 AM

Doppler Radar Base Reflectivity At 12:17 AM

Roads across northern Wise and Dickenson counties became slick around and just after Midnight before 
a concentrated snowstreak ( band of heavy snow ) developed and moved south across Wise County into Norton-Wise and the High Knob Massif after 2:00 AM.  Only heaviest snow is represented by these images.

Doppler Radar Base Reflectivity At 12:26 AM

Doppler Radar Base Reflectivity At 12:36 AM

Doppler Radar Base Reflectivity At 12:46 AM

Doppler Radar Base Reflectivity At 12:55 AM

Doppler Radar Base Reflectivity At 1:07 AM

Doppler Radar Base Reflectivity At 1:15 AM

Doppler Radar Base Reflectivity At 1:25 AM

Doppler Radar Base Reflectivity At 1:34 AM

Doppler Radar Base Reflectivity At 1:44 AM

Doppler Radar Base Reflectivity At 1:54 AM

Doppler Radar Base Reflectivity At 2:03 AM

Doppler Radar Base Reflectivity At 2:16 AM

Doppler Radar Base Reflectivity At 2:25 AM

Doppler Radar Base Reflectivity At 2:35 AM

Doppler Radar Base Reflectivity At 2:45 AM

Doppler Radar Base Reflectivity At 2:55 AM

A general 1-2" of snow accumulated amid the snowstreak, with locally more in places that got repeated hits by multiple squalls.

The CAM at UVA in Wise captured the heavy snow as it moved across the town of Wise, which previously had missed much of the snow during the first two phases of this event ( February 15-16 ).


University of Virginia's College In Wise
February 17, 2013 ( 2:29 AM to 2:52 AM )

Click consecutively on images for motion

Observe how distant lights disappear as 
the snow becomes moderate-heavy.

Snow Beginning To Fall In Far Distance
University of Virginia's College In Wise At 2:29 AM

University of Virginia's College In Wise At 2:31 AM

University of Virginia's College In Wise At 2:33 AM

University of Virginia's College In Wise At 2:34 AM

University of Virginia's College In Wise At 2:35 AM

University of Virginia's College In Wise At 2:36 AM

University of Virginia's College In Wise At 2:37 AM

University of Virginia's College In Wise At 2:38 AM

University of Virginia's College In Wise At 2:39 AM

University of Virginia's College In Wise At 2:40 AM

University of Virginia's College In Wise At 2:41 AM

University of Virginia's College In Wise At 2:42 AM

University of Virginia's College In Wise At 2:43 AM

University of Virginia's College In Wise At 2:44 AM

University of Virginia's College In Wise At 2:45 AM

University of Virginia's College In Wise At 2:46 AM

University of Virginia's College In Wise At 2:47 AM

University of Virginia's College In Wise At 2:48 AM

University of Virginia's College In Wise At 2:49 AM

University of Virginia's College In Wise At 2:50 AM

University of Virginia's College In Wise At 2:51 AM

University of Virginia's College In Wise At 2:52 AM

Additional light snow and snow showers 
fell into mid-morning on February 17.

February 17, 2013 at 8:49 AM
Along the Tennessee Valley Divide
Snow Falling Upon The Long Ridge Orchard
Photograph by Wayne Riner - © All Rights Reserved.



High Knob Massif
Winter Beauty Shots

February 16, 2013
Beauty of Rime & Rime Flakes In The Air
Majestic RIME of High Knob Crest Zone
Photograph by Roddy Addington - © All Rights Reserved.


High Knob Massif
Special Effects of Light On Rime
Photograph by Roddy Addington - © All Rights Reserved.

( Before the Snow Squalls )
Afternoon of February 16, 2013
Looking Across The High Knob High Country
Photograph by Roddy Addington - © All Rights Reserved.

Little Stony Basin of High Knob Massif
Special Effects of Winter 2012-13
Photograph by Roddy Addington - © All Rights Reserved.

Just a big ole...

WOW!

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