Saturday, December 7, 2013

The Stormy Pattern of December 2013


December 7, 2013
Long Ridge of Sandy Ridge
Along The Tennessee Valley Divide At 12:37 PM
Ice & A Little Snow Amid Prolonged Freezing Fog
Photograph by Wayne Riner - © All Rights Reserved.

The High Knob Landform

Although heavy rain ultimately proved to be the main impact of this stormy December pattern, a notable and prolonged period of freezing rain to freezing fog, and a little snow, coated elevations above 1800-2000 feet across Wise & Dickenson counties from early evening hours of December 6 throughout December 7.

A final wave in this series produced a nasty mix of freezing rain, sleet, and snow in locations along and NW-N-NE of the High Knob Massif and Tennessee Valley Divide into early hours of December 10 ( with ice storm conditions again amid upper elevations in the High Knob Massif ).  The heaviest snow fell along Pine Mountain.

December 7, 2013 at 1:26 PM
University of Virginia's College In Wise Live CAM
Courtesy of Alex Edwards & Computer-Math Department

Fog this thick, with visibility less than 0.25 mile for 21-30+ hours, should have produced a Freezing Fog Advisory.  Do you think the TRI area would have fog this thick, that long, with no Advisories at SUB-freezing temperatures?

December 7, 2013 at 9:11 PM
University of Virginia's College In Wise Live CAM
Courtesy of Alex Edwards & Computer-Math Department

December 7, 2013
Lonesome Pine Airport Observations For Wise



More than 21 consecutive hours with visibility 
mostly below 0.25 mile amid freezing fog in Wise.

December 8, 2013
Lonesome Pine Airport Observations For Wise

The basic story was told by this Long Ridge 
CAM which faces into the northerly winds.

December 7, 2013 at 1:25 PM
Nora 4 SSE - Long Ridge CAM Iced Over
Courtesy of Wayne & Genevie Riner


High Knob Massif
Heavy Icing December 6-7
( Freezing Rain to Freezing Fog With N-NE Flow )

December 8, 2013 at 10:15 AM
High Knob Massif - State Route 619
Trees Droop With Heavy Ice Formation
Photograph by Roddy Addington - © All Rights Reserved.

Note these scenes by Photographer Roddy Addington were taken on December 8 after temps warmed into mid-upper 30s and some melting had already occurred.  This icing was mostly a product of freezing rain Friday that gave way to prolonged Freezing Fog throughout Saturday ( December 7 ).

Freezing rain started along windward facing slopes of the High Knob Massif between 4:00 & 5:00 PM December 6, with limbs breaking by 10:00 PM as icing became heavy on trees.

December 7, 2013 at 2:32 PM
Freezing Fog On Eagle Knob of High Knob Massif 
Photograph by Steve Blankenbecler - © All Rights Reserved.

Numerous residents, like Joe & Darlene Fields of the High Chaparral community, encountered tree limbs in roads with significant icing on trees along windward slopes-crests of the massif.

High Knob Massif
Wise County, Virginia
December 8, 2013 at 10:52 AM
Heavy RIME-Like Ice Formation
Photograph by Roddy Addington - © All Rights Reserved.

Note that ice formed in a manner similar to rime, amid prolonged freezing fog, but was MUCH harder, shinier, and clearer in nature than the more typical rime that forms in association with many snow events.  A widespread glaze to plain rain contributed little additional accumulation to these scenes, as temps warmed above freezing at high elevations quicker than at lower elevations, into early morning hours of December 8.

The elevation span of this ice formation was from base to summit along windward facing slopes, with respect to northerly air flow trajectories, but much higher along southern slopes leeward of main crestlines toward the Clinch River side.

Elevation 3308 feet
City of Norton Reservoir
Trees Bent With Weight Of Heavy Icing
Photograph by Roddy Addington - © All Rights Reserved.

The ice was beautiful as 
Roddy well documented.

December 8, 2013 at 9:44 AM
Benges Basin of High Knob Massif
Gorgeous Light Illuminates Significant Icing
Photograph by Roddy Addington - © All Rights Reserved.

Rod Addington Photography

Freezing temperatures were first reported in Wise at 7:11 PM December 6, by the Wise RAWS, and later at 8:15 PM by Lonesome Pine Airport.

December 6, 2013
Lonesome Pine Airport Observations For Wise

 With 5 different observation sites in the Norton-Wise and Sandy Ridge corridor, at about the same elevation, LNP was the last to show freezing as it has a small and typically unimportant 1-2 degree Fahrenheit warm bias.

Nora 4 SSE
December 7, 2013
Southern Dickenson County
Early Afternoon Ice Accumulation
Photograph by Wayne Riner - © All Rights Reserved.

Ice accumulations were substantial down into the 2000 to 3000 foot elevation zone northward of the High Knob Massif across much of the remainder of Wise & Dickenson counties, but not as heavy ( to break trees ) like in the High Knob Massif area.

Nora 4 SSE
December 7, 2013
Along the Tennessee Valley Divide
Early Afternoon Ice Accumulation
Photograph by Wayne Riner - © All Rights Reserved.

December 7, 2013
A Raw & Icy December Afternoon
Photograph by Wayne Riner - © All Rights Reserved.

Strong rises were observed on creeks into evening hours of December 6, despite the considerable reduction in run-off with icing at mid-upper elevations above 2000 feet elevation.

Upper Tennessee River Basin
Northern Scott County, Virginia
Big Stony Creek of Clinch River
Drainage Basin of 41.9 Square Miles ( In Total )
Above The Clinch River Confluence

Big Stony Creek came within 14" of flood stage in northern Scott County, Va., with a rapid rise and drop as typical of that flashy mountain basin.

Rainfall totals of 1.75" to 2.50"+ were common across Lee, Wise, northern Scott, and Dickenson counties with this first major wave of precipitation.

The second major wave, during December 8-9, produced 1.50" to 2.50"+ rain amounts across these same locations.

December 1-15, 2013
Clinch River At Speers Ferry
Gage Height ( 9.3 feet of Total Rise )

The Clinch River had 9.3 vertical feet of rise 
at Speers Ferry in southern Scott County, Va., cresting around 5 feet below flood stage.  The crest was close to flood stage ( red line below ) above Tazewell in Claiborne County, Tennessee. 

December 1-15, 2013
Clinch River Above Tazewell, Tennessee

The Powell River had 10.2 vertical feet of rise near Jonesville in Lee County, Va., cresting around 
6 feet below flood stage.

December 1-15, 2013
Powell River Near Jonesville
Gage Height ( 10.2 feet of Total Rise )

The Cumberland River crested just above flood stage downstream in Williamsburg, Ky., after 
16.3 vertical feet of total rise.

December 1-15, 2013
Cumberland River At Williamsburg
Gage Height ( 16.3 feet of Total Rise )

Precipitation totals of 4.00" to 5.00"+ were common in counties along either side of the Virginia-Kentucky border during the 
December 5-10 period ( reference list ).

December 7, 2013
Shrouded Amid Afternoon Freezing Fog
Photograph by Wayne Riner - © All Rights Reserved.

The final wave in this series produced widespread icing again in locations along and NW-N-NE of the High Knob Massif - Tennessee Valley Divide, with a transition to mostly snow northwest of a line from Pound to Clintwood to Grundy.

December 10, 2013 at 12:41 PM
Nora 4 SSE - Long Ridge CAM Iced Over
Courtesy of Wayne & Genevie Riner

Ice storm conditions developed once again in the High Knob Massif, especially the upper elevations where temperatures were in the 20s to around 30 degrees throughout this event.

Only a warm layer aloft, well above the high mountain crestlines, prevented this from becoming a heavy snow setting to prove once again that temperatures aloft ( and thicknesses ) are CRITICAL to what precipitation type reaches the surface
( even on the highest Appalachian summits ).

December 10, 2013 at 12:38 PM
Eagle Knob of High Knob Massif
Ice Shrouded In Wake of Ice Storm Conditions
Photograph by Steve Blankenbecler - © All Rights Reserved.

A strong precipitation gradient developed across southwest Virginia during the December 5-10 period of 2013, much like during the analog month of December 1978, with decreasing totals east of the Cumberland Mountain Overthrust Block. 

Precipitation Totals
For December 5-10, 2013
( Official 8" NWS Gauge Sites Unless Noted )

( U.S. Forest Service )
Wise RAWS: 3.60"

Clintwood 1 W: 4.04"

City of Norton WP: 4.49"

( VDOT Automated Rain Gauge )
Little Stone Mountain: 5.58"

High Knob Massif
Upper Tennessee River Basin
Morning Hours of December 8, 2013
Amid The Transition Between Liquid And Solid
Photograph by Roddy Addington - © All Rights Reserved.

East of the Cumberland Block

Richlands: 2.56"

Saltville 1 N: 1.99"

Galax WTP: 1.89"

Lebanon: 1.86"

Abingdon 3 S: 1.83"

Blacksburg: 1.71"

Pulaski: 1.67"

Burkes Garden: 1.62"

Meadows of Dan 5 SW: 1.56"

Staffordsville 3 ENE: 1.40"

Copper Hill: 1.34"


December 17, 2013
Fast Moving Clipper Snow
Upper Elevations of High Knob Massif

A dynamic and fast moving clipper system dropped accumulating snow upon upper elevations, above 3000 feet, during the late afternoon-early evening of December 17.

December 17, 2013 at 5:47 PM
Eagle Knob of High Knob Massif
Moderate-Heavy Snow & Blowing Snow
Photograph by Steve Blankenbecler - © All Rights Reserved.

As low morning clouds finally broke, on gusty SW winds, a brief period of clearing gave way to rapid cloud and precipitation development during the 3:00 to 5:00 PM period.

Accumulations varied from 1-2" above 3500 feet
down to nothing between 2500-3000 feet and below.

December 17, 2013 at 1:15 PM
NASA Visible Image At 1815 UTC

December 17, 2013 at 1:45 PM
NASA Visible Image At 1845 UTC

December 17, 2013 at 2:15 PM
NASA Visible Image At 1915 UTC

December 17, 2013 at 2:45 PM
NASA Visible Image At 1945 UTC

December 17, 2013 at 3:02 PM
NASA Visible Image At 2002 UTC

December 17, 2013 at 3:15 PM
NASA Visible Image At 2015 UTC

While accumulating snow was expected, the transition to sticking snow in middle elevations 
( between 2000 and 3000 feet ) did not occur as temperatures dropped slower than forecast by models 24-hours before.

( 7:00 PM December 16, 2013 )
00z Model Run December 17, 2013
Forecast Sounding Above Wise, Virginia

( 7:00 PM December 17, 2013 )
00z Model Analysis December 18, 2013
Actual Initialization Sounding Above Wise

A bright snow glare 
was seen December 18.

December 18, 2013 at 1:24 PM
Eagle Knob of High Knob Massif At 4189 Feet
Photograph by Steve Blankenbecler - © All Rights Reserved.



December 20, 2013
Mountain Waves On SW Winds
High Knob Landform - Black Mountain Corridor

As I have well documented for years, a distinct orographic effect influences weather conditions within the High Knob Landform - Black Mountain corridor when SW winds become strong and gusty.

Such was the case during December 19-20, 2013 when MAX temperatures within this corridor were significantly cooler than adjacent locations.  More moisture during December 20 made the effect highly visible in the form of persistent, long-lived mountain waves.  This is an ongoing event, part of the major storm system documented in the teleconnection-outlook section later.

Time Series Looking Upward
Click On Images In Picture Viewer For Motion

December 20, 2013 at 2:09 PM
University of Virginia's College In Wise
Mountain Waves Above Norton-Wise Area
Courtesy of Alex Edwards - Computer & Math Department

December 20, 2013 at 2:10 PM
University of Virginia's College In Wise
Mountain Waves Above Norton-Wise Area
Courtesy of Alex Edwards - Computer & Math Department

December 20, 2013 at 2:11 PM
University of Virginia's College In Wise
Mountain Waves Above Norton-Wise Area
Courtesy of Alex Edwards - Computer & Math Department

December 20, 2013 at 2:12 PM
University of Virginia's College In Wise
Mountain Waves Above Norton-Wise Area
Courtesy of Alex Edwards - Computer & Math Department

December 20, 2013 at 2:13 PM
University of Virginia's College In Wise
Mountain Waves Above Norton-Wise Area
Courtesy of Alex Edwards - Computer & Math Department

December 20, 2013 at 2:14 PM
University of Virginia's College In Wise
Mountain Waves Above Norton-Wise Area
Courtesy of Alex Edwards - Computer & Math Department

December 20, 2013 at 2:15 PM
University of Virginia's College In Wise
Mountain Waves Above Norton-Wise Area
Courtesy of Alex Edwards - Computer & Math Department

December 20, 2013 at 2:16 PM
University of Virginia's College In Wise
Mountain Waves Above Norton-Wise Area
Courtesy of Alex Edwards - Computer & Math Department

December 20, 2013 at 2:17 PM
University of Virginia's College In Wise
Mountain Waves Above Norton-Wise Area
Courtesy of Alex Edwards - Computer & Math Department

December 20, 2013 at 2:19 PM
University of Virginia's College In Wise
Mountain Waves Above Norton-Wise Area
Courtesy of Alex Edwards - Computer & Math Department

December 20, 2013 at 2:24 PM
University of Virginia's College In Wise
Mountain Waves Above Norton-Wise Area
Courtesy of Alex Edwards - Computer & Math Department

Advancing 1 hour & 2 minutes in time

December 20, 2013 at 3:26 PM
University of Virginia's College In Wise
Mountain Waves Above Norton-Wise Area
Courtesy of Alex Edwards - Computer & Math Department

December 20, 2013 at 3:27 PM
University of Virginia's College In Wise
Mountain Waves Above Norton-Wise Area
Courtesy of Alex Edwards - Computer & Math Department

December 20, 2013 at 3:28 PM
University of Virginia's College In Wise
Mountain Waves Above Norton-Wise Area
Courtesy of Alex Edwards - Computer & Math Department

December 20, 2013 at 3:29 PM
University of Virginia's College In Wise
Mountain Waves Above Norton-Wise Area
Courtesy of Alex Edwards - Computer & Math Department

December 20, 2013 at 3:29 PM
University of Virginia's College In Wise
Mountain Waves Above Norton-Wise Area
Courtesy of Alex Edwards - Computer & Math Department

December 20, 2013 at 3:30 PM
University of Virginia's College In Wise
Mountain Waves Above Norton-Wise Area
Courtesy of Alex Edwards - Computer & Math Department


Time Series Looking Down
Click On Images In Picture Viewer For Motion

December 20, 2013 At 12:15 PM
NASA Visible Image At 1715 UTC

December 20, 2013 At 12:15 PM
NASA Visible Image At 1715 UTC

December 20, 2013 At 12:45 PM
NASA Visible Image At 1745 UTC

December 20, 2013 At 1:15 PM
NASA Visible Image At 1815 UTC

December 20, 2013 At 1:32 PM
NASA Visible Image At 1832 UTC

December 20, 2013 At 2:02 PM
NASA Visible Image At 1902 UTC

December 20, 2013 At 2:15 PM
NASA Visible Image At 1915 UTC

December 20, 2013 At 2:45 PM
NASA Visible Image At 1945 UTC

The GREAT warm wave of December 2013, at least as hype has it, was not as great amid this corridor with both lower temperatures and gusty winds 
( especially at high elevations ) making conditions feel much cooler during December 19-20.

December 20, 2013
*Midnight to 6:00 PM Hourly Temperatures
City of Norton - AWS Weather Station Readings
The PM MAX was 52 degrees at the Norton AWS,
and 55 degrees for the 24-hour period ending at
9:00 AM December 21

*The MAX was 51 degrees at the Norton Water Plant
for the 24-hour period ending at 9:00 AM December 21

Conditions From 4:30 AM to 6:30 PM
Nora 4 SSE - Automated Davis Pro2 Station
Site of Official NWS Cooperative Station

Day time MAX temperatures reached only mid 40s atop the High Knob Massif during Dec 19-20, and at the FAA Radar Site on Black Mountain during December 20.

By contrast, locally strong wind gusts pushed MAX temperatures into the 60-65 degree range across lower elevations of the Russell Fork & Levisa Fork basins, with downsloping to the north and northeast of the SW airflow mountain wave generation corridor, during December 20. 

Temperatures finally warmed in the High Knob Massif area during December 21, via more southerly flow, with MAX temperatures of 64 degrees at the Norton Water Plant, 65 degrees at the AWS site of Norton Elementary School, and 66 degrees at Nora 4 SSE on Long Ridge ( with middle 50s atop the High Knob Massif ).


Global Teleconnections
Beginning To Show Signs Of Change
Could A Persistent Hudson Bay Polar Vortex
And Teleconnections Finally Work Together To
Enhance Winter In The Southern Appalachians?

Currently A Trend To Be Monitored

Increasingly bitter air felt December 23-24 will become a more common factor in eastern USA weather conditions if global teleconnections finally begin to work with, instead of against, a persistent lobe of the Polar Vortex centered near Hudson Bay in eastern Canada.  Currently, there are pros and cons, for and against, this happening heading into January 2014.

Perhaps, a more appropriate phrasing of the above might be, if the Polar Vortex changes as to allow for a more favorable flow regime and teleconnection pattern to develop across the Northern Hemisphere to permit enhancement of wintry conditions into the southern Appalachians and SE USA.

While the main lobe of a bitter Polar Vortex has proven to be persistent, with staying power, amid its counter-clockwise circulation around the Hudson Bay region of eastern Canada, global teleconnections that control the large-scale flow regime across the Northern Hemisphere have been opposed to the influence of this Polar Vortex upon the southern Appalachians and SE USA.  Or, has the Polar Vortex been opposed to them??

Opposed with respect to establishment 
of prolonged Wintry Conditions
amid this region.

That is why December 2013 has been a very wet month 
with FAR more rain than snow and frozen precipitation types across the southern Appalachians with no deep and prolonged troughing into the SE USA.

The question now, will these teleconnection trends continue or give way again to the same type of stormy, repetitive pattern observed since 
mid-late November 2013?

With intervals of SW Upper Flow dominating the Eastern USA, and especially SE USA, during periods of significant precipitation ( reference MEAN Dec 1-20 conditions ).


Actual Observed Conditions
December In Northern Hemisphere

Northern Hemisphere
December 1-20, 2013
30 MB Geopotential Height Anomalies

The Polar Vortex certainly shows up well on the 
30 MB Height Anomaly Chart for December 1-20 
( above ).

Interesting that upper air anomalies across the 
SE USA during December have been a reflection of 10 MB Geopotential Height Anomalies ( below ).

Now it is known that is not just by chance, as the troposphere + stratosphere are an intimately coupled system analogous to the well studied ocean-atmosphere coupled system ( and, of course, part of that system too ). 

Northern Hemisphere
December 1-24, 2013
10 MB Geopotential Height Anomalies

In reality, the Polar Vortex 
has gotten very strong.


Note above that temperatures between 60N and 90N are currently at near record low levels, implying a very strong vortex.

December 25, 2013
Temperatures Above The North Pole
Temperatures Above The North Pole are now at
RECORD COLD levels ( near -130 F below zero )

December 25, 2013
More Simplified Illustration Of Polar Vortex State
A new chart will be needed here if it keeps dropping!

As would be expected, zonal mean winds at 60N and 10 MB are also at or near record high levels, since a very strong or cold vortex = strong winds.


If you are a true winter fan the above has already been good if you live in SE Canada or the northern USA, beneath or close to this increasingly frigid, swirling vortex.

However, since the vortex is so compact, at some distance from it the tendency has been for wild variations in temperatures with a persistent UP-DOWN regime dominated by SW Upper Air Flow, when push comes to shove, during significant precipitation events.

That is, in fact, what climatology of such 
powerful Polar Vortices would predict.

Reference The Stratospheric Section 
For More Information

Northern Hemisphere
December 1-20, 2013
500 MB Geopotential Height Anomalies

Even from the mean 500 MB Geopotential Height Anomalies, above for the December 1-20 period, it is evident that SW flow has dominated much of the eastern USA.  From the mean vector wind, below, it is perfectly clear as to why snow has been lacking for places south of the Ohio River and mean jet core ( with warm air aloft via the SW flow killing much snow in settings that, without such an influence, would have been productive ).

United States
December 1-20, 2013
500 MB Vector Wind Composite Anomalies

Mean temperatures have, of course, been above average southeast of the upper jet core ( but tempered and held in check by both the prolonged -EPO and the southern flanks of cold air swirling around the Polar Vortex ).

Northern Hemisphere
December 1-20, 2013
850 MB Air Temperature Composite Anomalies

When cold air has been in place, the lack of a Great Lake fetch to transport moisture has also greatly reduced December snowfall across the southern Appalachians ( even Snowshoe Mountain, Wv., 
in the central Appalachians, only had 1" of snow 
on the ground Christmas Morning ).

United States
December 1-24, 2013
850 MB Vector Wind Composite Mean

A very long-lived anomaly has been the above average 500 MB heights across the eastern and northern Pacific Ocean, centered across the Aleutians, which have been in opposition to the mean climatological standing wave pattern featuring a Mean Aleutian Low 
( which cranks out Wave 1 forcing ).

Northern Hemisphere
October 1 to December 20, 2013
500 MB Geopotential Height Anomalies

This dominated the October 1 to December 20 period, with a mean SW to NE tilted upper trough centered over western-central portions of the USA.

United States
October 1 to December 20, 2013
500 MB Vector Wind Composite Anomalies

With a mean WSW-SW upper air flow regime 
across regions southeast of the trough axis.


So it is no surprise to find that episodes of strong Wave 2 activity have been working upon the atmosphere since late October through December. 


The amplitude of Wave 2 decreasing upward
and not yet able to penetrate the Polar Vortex
or weaken the Polar Night Jet



( Updated December 26, 2013 )
Upcoming Wave Forcing
Could Impact Early January Storm Events
( Putting The Squeeze On The Polar Vortex )

The ECMWF model is forecasting very strong Wave 2 forcing to develop during the next week, likely in response to a strongly positive Mountain Torque event across the Himalayas in recent days. 


Positive mountain torque events are always important since they can be a signal for upcoming changes in major teleconnection patterns, such as the PNA and AO, amid the Northern Hemisphere.


The possible shift from recent prolonged -PNA 
and +AO states would be an example if realized.

Eliassen–Palm Flux Vectors
Total Wave For Troposphere + Stratosphere

Eliassen–Palm Flux Vectors
Total Wave For Stratosphere


( 12z Model Run December 25, 2013 )
Wave 2 At 7 AM Christmas Morning

Note the 1000+ meter increase in displacement of air amid 
upper portions of the stratosphere by the beginning of January.

Forecast For 12z January 1, 2014
( 12z Model Run December 25, 2013 )
ECMWF Model Wave 2 Forecast Day 7

As Wave 2 wanes a surge of Wave 1 forcing 
is also currently forecast to develop which is
a natural reaction as the squeeze, or compression,
exerted by Wave 2 on the vortex is being released.

This forecast of strong Wave activity is certainly important and will need to be closely followed, as any subsequent strong wave forcing will then have better chances to actually penetrate into the polar vortex core and weaken it ( and the potent Polar Night Jet ).

( 12z Model Run December 25, 2013 )
Wave 1 At 7 AM Christmas Morning

Forecast For 12z January 4, 2014
( 12z Model Run December 25, 2013 )
ECMWF Model Wave 1 Forecast Day 10

While the full impact of this forcing upon regional weather conditions in the southern Appalachians is not yet known, a squeeze will be placed upon the Polar Vortex by the potent Wave 2, and subsequent Wave 1, forcing heading into early January 2014.

Perhaps the best way to see this is by starting at the top of the stratosphere, where impacts will be greatest, and working downward to the bottom.

( 7 AM Local Time )
12z Model Run December 25
Analysis of 1 MB Stratospheric Level

( 7 AM Local Time )
12z Model Run December 25
Forecast For 7 AM January 4, 2014
Forecast of 1 MB Stratospheric Level

( 7 AM Local Time )
12z Model Run December 25
Analysis of 10 MB Stratospheric Level

( 7 AM Local Time )
12z Model Run December 25
Forecast For 7 AM January 4, 2014
Forecast of 10 MB Stratospheric Level

( 7 AM Local Time )
12z Model Run December 25
Analysis of 50 MB Stratospheric Level

( 7 AM Local Time )
12z Model Run December 25
Forecast For 7 AM January 4, 2014
Forecast of 50 MB Stratospheric Level

( 7 AM Local Time )
12z Model Run December 25
Analysis of 100 MB Stratospheric Level


( Updated December 29, 2013 )
Polar Vortex Under Attack
End Of Intensification Could Be Near

( 7 AM Local Time )
12z Model Run December 29
Analysis of 100 MB Stratospheric Level


Note that this "squeeze" of the vortex by a 2-Wave attack enhances troughing over the USA amid mid-upper levels of the stratosphere, with weakening toward the bottom where by Days 7-10 the best troughing is now toward the eastern USA.

( 7 AM Local Time )
12z Model Run December 29
Forecast For 7 AM January 8, 2014
Analysis of 100 MB Stratospheric Level

The Polar Vortex, which has been a powerhouse, 
is starting to show signs of impact.  Will this lead eventually to a breakdown or even a major SSW 
( sudden stratospheric warming )?  It is too soon to tell but these are positive signs for winter fans in the USA ( including the southern Appalachians ).

Although still far away from a technical SSW, which may or may not occur later, this powerhouse polar vortex is now showing signs of weakening via continued, prolonged impact of potent Wave 2 
( and coming Wave 1 ) forcing.

( 7 AM Local Time )
12z Model Run December 25
Zonal Mean State Of Temperature

( 7 AM Local Time )
12z Model Run December 29
Zonal Mean State Of Temperature

To illustrate that the core of this Polar Vortex is being impacted, note in the picture viewer that the temps have already started to warm a little and are forecast by the ECMWF to warm more by DAY 10 ( January 8 ) above the North Pole at 30 MB
( above 90 degrees North ).

( 7 AM Local Time )
12z Model Run December 29
Forecast For 7 AM January 8, 2014
Forecast Of Zonal Mean Temp State

( 7 AM Local Time )
12z Model Run December 25
Zonal Mean Zonal Wind State

Note that wind speeds have decreased in the past 4 days.

( 7 AM Local Time )
12z Model Run December 29
Zonal Mean Zonal Wind State

Again, to illustrate the point, note that at 60 N and 30 MB that westerly wind speeds are now forecast to decrease to around
40-45 m/s by DAY 10.  This shows that the PNJ ( Polar Net Jet ) is weakening with time as temperatures in the core of the vortex begin to warm ( decreasing the horizontal temperature gradient across the vortex which is being squeezed ).  Climatology says this is a positive sign for winter fans in mid latitudes of the USA ( and later western Europe ) should it continue.

Re-intensification often occurs, but perhaps not, at least not back to its former powerhouse state?  Time will soon tell.

( 7 AM Local Time )
12z Model Run December 29
Forecast For 7 AM January 8, 2014
Forecast Of Zonal Mean Zonal Wind

Models have been giving mixed signals with respect to the pattern across the southern Appalachians, and runs in coming days should be interesting given these new stratospheric changes.

That is the wisdom which should be taken from past climatology
of such powerful, compacted polar vortex states ( which tend to promote more SW flow at lower latitudes and maintain +AO/NAO states that keep the "Bermuda High" pumped relative to normal
( making SE USA troughs harder to develop and keep ).

Forecast's of DEEP eastern USA troughs have ended up verifying much more shallow in nature, keeping the southern Appalachians along the southern periphery of cold air ( essentially cutting off Great Lake moisture from these latitudes with more WNW-WSW flow across the Lakes ).  System snows have been limited due to the bulk of precipitation falling amid SW flow intervals ruled by advections of milder air.

In other words, given repeated past forecast's of bitter arctic air plunging deeply south into the E-SE USA that did NOT happen during December, it is best not to buy into future forecasts of the same if the polar vortex and teleconnections do not really change for this region.

With the above noted, more bitter air is likely to arrive by New Year's Day but again be progressive with the truly bitter, barbaric, air remaining well to the north and northeast.  Of course, at this time of year, it is always an "evolving" situation but the big picture has been pretty clear ( at least, up to now ).

When there is so MUCH COLD so CLOSE it can be easy to get carried away, since it would only take relatively small mileage changes to make HUGE differences; however, the above is what climate science says about the "big picture."  A single storm that would really "wrap up" could easily alter the amount of cold reaching the southern Appalachians during any given event
( with a Polar Vortex lobe in SE Canada ).

Such an option is certainly on the table ( that certain storms "wrap up" in this energetic pattern ) amid what is clearly a continued UP and DOWN temperature regime.

All of the above remains true; however, if the vortex lobe is squeezed south then this may be 
a case where stratospheric changes are leading teleconnections which have not yet fully responded.  More will be known in a few days.

Perhaps the significance of this can be shown 
by the potential vorticity field amid the lower stratosphere, as analyzed and forecast by the ECMWF Model.

( 7 AM Local Time )
12z Model Run December 29
Current View In Lower Stratosphere
Potential Vorticity At 475K

Note how the Polar Vortex is literally being squeezed south into the USA ( below ) 
during the next 10 days.

( 7 AM Local Time )
12z Model Run December 29
Forecast In Lower Stratosphere
7:00 AM January 8, 2014
Potential Vorticity At 475K

Amid the troposphere, the ECMWF has already responded by showing a much farther south track with the major winter storm timed for January 5-6.

Of course, the above is very early and 
will have to be replicated on new runs ahead.


December 27-28, 2013
Updated Teleconnections

A Preface To Using Teleconnections
A problem is that the teleconnections shown below are based upon models.  In climate science models must always be looked upon as imperfect, flawed with errors that are initially present or creep into their forecast world via nonlinear actions in which they can not properly handle and account for over time.  It is the job of a forecaster, or climate scientist, to understand and adjust for these flaws and known biases ( at least, in as much as current understanding allows ).

Models are, at best, guidance to be used against real-time accounting of teleconnections predicted from actual height anomalies and patterns present NOW ( not those forecast to be present by models on some future day ).  That takes skill, practice, and a good deal of luck at any given time on part of the climate scientist to pin down a future pattern. It also takes a solid foundation based upon past climatology of similar atmospheric settings.

Thus, it is absolutely critical to always look at current daily conditions and anomalies, and to follow their development and evolution over time ( from the present backwards for best understanding of possible future changes since it is important to understand how the NOW, or present, has come to be ).  

When model trends agree, replicate, and support teleconnections which climatology shows has produced specific flow regimes in the past then confidence can greatly increase in future flow field predictions.

Teleconnections can be thought of as being a guide to the Hemispheric flow regime while embedded eddies amid the flow field, which constantly form and dissipate through space and time, are the synotpic to mesoscale features associated with day to day weather changes.  Certain teleconnective patterns, or combinations, make eddies more able to draw energy from the large-scale flow regime to amplify over certain regions, while dissipating above other regions, and forms a way to access the likelihood of a predicted future storm.

Teleconnections, when used properly with climatology, are powerful tools that can support or oppose model predictions ( often winning out over even composite model forecasts if they are opposed to the solution ).

A most recent example being consistent future model forecasts of brutal coldness overtaking the southern Appalachians which have not verified, being against teleconnections.  As time got closer to such predictions, time and time again, model solutions turned away from the radical forecasts toward more timid settings fitting that which teleconnections supported in the first place.

Now, IF teleconnections continue to trend toward support of eastern USA coldness as the New Year begins, the opposite setting emerges in that future model projections may end up not being cold enough ( e.g., at ranges of 5-10+ days ) for this region.

The teleconnection trend as of January 4, 2013 favors an intense but progressive hit of brutal cold forced by a Wave 2 attack on the Polar Vortex, with compressional deformation, then a return to SW Upper Flow for a period of time ( i.e., milder & wetter ) before cold likely returns.

The UP & DOWN pattern continues.

Teleconnection Forecast
Updated January 4, 2014



North Atlantic Oscillation

NAO Trend Is To Remain Positive
After The Major Arctic Blast of Jan 6-7

Pacific-North American Oscillation
+PNA Emerges For Major Arctic Blast
then shifts back into previous -PNA mode

The -EPO has been offsetting, at least to some extent, the -PNA while the +WAF ( wave activity flux ) from the Hudson Bay vortex and SE Canada snowpack has been working against the +NAO/AO combination.  Who ever dared think that ENSO
is the only game in town!

Eastern Pacific Oscillation

The battle has been on between a Hudson Bay vortex and expansive eastern Canada snowpack & coldness, with wintry feedback potential, and global teleconnections that otherwise favored milder eastern USA ( especially SE USA ) conditions.

( Milder meaning relative to "normal" for this time of year )
That was verified in December 2013 which will end somewhat
milder than average across the southern Appalachians.

No "old fashioned" winter is going to develop across the southern Appalachians, or central mountains, until global teleconnections come into much better alignment for such an occurrence to happen and have staying power.

An "old fashioned" winter is one featuring prolonged cold and building snowpack from valley to summit, with snowfall measured by FEET, not inches, amid the High Knob Massif and other favored snowbelt locales along the southern-central Appalachians.

The analog season of December 1978 ( used for recent wetness ) eventually saw that happen during January-February 1979,
which were very cold, snowy months in the mountains.

While the November 1978 polar vortex setting was nearly identical to November 2013, the evolution of the polar vortex during December 1978 was MUCH different from that observed during December 2013.  So that analog now appears to have run out its course ( the future is now uncharted from the 1978 view.  That is, now it must be based upon analogs from past years that are more analogous to current conditions ).

Could there be a White Christmas in 2013?  Certainly.  But if you are a fan of "big-time" winter it would be most favorable, given a nearby Hudson Bay vortex, if the PNA turned strongly positive, the EPO remained negative, and the NAO became East-Based and negative in phase.  That would be truly "big-time" and are now trends to follow into the new  year of 2014.

Christmas Morning 2013 was white in parts of Wise County.

Having snow deposition to the north is always a good thing if you are a winter fan, especially if it has staying power and expands south over time.  The southward expansion with staying power being due to a positive feedback that naturally works to push the baroclinic zone southward ( the zone of maximum north-south temp gradient = a storm track to produce snow farther south ).

High Knob Massif
Beauty In An Ice Storm
Photograph by Roddy Addington - © All Rights Reserved.

When a positive feedback for winter development ( snowpack with persistence ) combines with teleconnections supporting 
upper air troughing over the same region that 
typically = a big time shift into WINTER MODE.

( Like has occurred this month from
the Rockies into the upper Midwest )

The snowpack that has expanded across eastern Canada and central-northern portions of the USA 
is already in place, such that if and when global teleconnections shift in favor of deep eastern USA troughing the pattern could rapidly shift into big-time winter mode for the southern Appalachians.  

However, until this combo can get its act together such a setting can not easily develop or be sustained south of the Ohio River.
( written in early December 2013 ).

This page is under construction.  Check back for updates.

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