September 1, 2012
Evening Thunderhead Above The Highlands
Photograph by Wayne Riner - © All Rights Reserved.
Wayne Riner Photograph Thoughts...
"It could be a view from a high flying aircraft; however, it was taken from Long Ridge."
Tropical skies and localized downpours produced some of the most humid conditions of the year as the dissipating remnants of former hurricane Isaac spread across the southern Appalachians to open Meteorological Autumn 2012.
Muggy air generated the warmest night of the year in the City of Norton and Clintwood, with minimums of 68 and 70 degrees, respectively, on September 5.
1715 UTC ( 1:15 PM Local Time )
The Swirl Of Isaac - September 2, 2012
NASA GOES 13 Visible Image
Localized 3.00"+ rain amounts fell along either side of the Virginia-Kentucky border, with up to 5.84" in the Meadows of Dan along the Blue Ridge, but most places got much less as Isaac faded into climatological history.
Autumn 2012
First Major Cold Front
The first major cold front of early autumn changed the pattern on September 8 with 0.50" to 1.00"+ of soaking rainfall, gusty winds, and a afternoon temp plunge into the 50s and 40s along and north of the High Knob Massif.
The arrival of this front was captured by the video camera of Wayne & Genevie Riner on Long Ridge.
Time Series Of Frontal Band
Click Consecutively On Images For Motion
Long Ridge At 12:32 PM - September 8, 2012
Awesome Morning Sunrise
Birch Knob of Pine Mountain
September 9, 2012
Cumberland Overthrust Block
Above Fog Layer of Morning Inversion
In the High Knob Massif the first half of September featured mean maximums in the 60s to lower 70s at highest elevations by day, with 50 to 55 degree average lows at night ( the coolest night featuring 30s to lower 40s in high valleys on September 11 ).
September 13, 2012
Majestic Evening Colors
Sunset Along The Tennessee Valley Divide
Global Connections
Major Autumn Storm Expected
September 17-18, 2012
A major league autumn storm system is expected to impact the Appalachians during September 17-18 as an unseasonably strong trough digs south out of Canada to trigger an anomalous, early season synoptic-scale rainfall event.
A forecast model spread of 1.00" to 5.00" of rainfall is being predicted across the southern Appalachians during the September 17-18 period. Folks living along streams and in poor drainage, flood prone locations should monitor water levels closely later Monday and Tuesday as rain increases in both amount & intensity.
September 15, 2012
European Model Analysis At 8:00 PM
While above charts are subject to change with new runs of the model, this scenario has been very consistent for consecutive days on ECMWF forecasts.
A deep 984 MB ( 29.06" ) low blasting the Aleutians, in the Gulf of Alaska, is helping drive this process by buckling the Polar Jet and aiding formation of a +PNA ridge complex along the western coastlines of North America.
September 15, 2012
Pacific Surface Analysis At 21:05 UTC
( Low Deepened to 984 MB by 0000 UTC )
This is part of a continuing hemispheric pattern change that started September 8-9 and kicks into high gear during the upcoming 5-10 day period as indicated by European Model 500 MB Height Anomaly forecasts.
September 15, 2012 at 8:00 PM
European Model 500 MB Height Anomaly
A situation to monitor for significant frost-freeze potential in coming days as this pattern fully develops across North America by the September 22-24 period.
Part of the higher than average confidence in this forecast scenario rests in a Super Typhoon named Sanba and convection associated with the Madden-Julian Oscillation ( MJO ) that is in position to feed energy into the polar westerlies ( aiding amplification ).
September 13, 2012 at 0450 UTC
High Resolution NASA Visible - Super Typhoon Sanba
Warmer than average sea surface temperatures
( SST ) across the North Pacific are associated with a cool phase of the Pacific Decadal Oscillation, or
-PDO teleconnection, which climate correlations tend to show are opposed to +ENSO phases ( * ).
A -PDO added to -ENSO ( La Nina ) and +PDO added to a +ENSO ( El Nino ) would tend to reinforce ENSO forcing
( wave trains interact in constructive ways ).
A -PDO added to +ENSO and +PDO added to a -ENSO tends to oppose ENSO forcing ( wave trains from their forcing tend to interact in destructive ways to reduce their mean climatological influences on the eastern USA ).
*Current trends are for a central-west based +ENSO ( El Nino ) during Winter 2012-13 which would favor colder than average conditions across the eastern USA and western Europe. Will this tendency be canceled or overwhelmed by a -PDO phase, and will anomalously warm SST remain over the northwestern Atlantic to tip the scales back toward a colder eastern USA? Stay tuned.
( Many other factors will also be at play ).
Teleconnection Forecasts
( Short-Term Outlook )
Climate anomalies that force weather changes in places far removed from where they occur are known as teleconnections.
Many are defined and used to anticipate weather changes, while many more teleconnections remain hidden amid the complexity of this climatic system ( a composite system of all living and non-living things in space and time ).
-NAO and ++PNA
Global Teleconnections
And Climate Correlations
An Orographic Forcing Season Perspective
While the southern Appalachians have four celebrated seasons with distinct and dramatic landscape changes, from a climatology perspective there are only two that rule!
1 ). The Orographic Forcing Season
*November-April
2 ). The Convective Season
*May-October
*May and October are often months of transition, and depending upon the year can be dominated by either climatic mode. More often than not, however, they are ruled by a mixture of both forcing and convective events. While either can occur during any month, orographic forcing is most likely the dominant mode observed during the November to April period.
When north to south temperature gradients develop across North America the atmosphere becomes more baroclinic ( density of the air is a function of both pressure and temperature ), such that synoptic-scale storm systems arise with winds that push against the topography.
In a most simplistic way, this leads to orographic forcing with its upsloping and downsloping.
In reality, orographic forcing is MUCH more complex and involves a host of parameters that dictate the nature of both daily weather conditions and longer term climate in locations resting within the mountains, as well as up and down stream of air flow trajectories interacting with them at different levels ( ** ).
**This includes a myriad of orographically generated waves whose amplitudes occasionally exceed their wavelengths to allow wave breaking ( i.e., overturning like ocean waves rolling toward a beach where frictional drag at the bottom, beneath the water, is increasingly "felt" by the waves to cause them to roll over and expend their transported momentum and energy ).
Note that the following teleconnection patterns could be looked at using different parameters from the 500 MB geopotential height field, but given general "smoothing" that occurs at 500 MB it is suitable for basic statistical correlations of mean climatic tendencies.
Maps below DO NOT indicate actual height departures and DO NOT imply strict causation by just a single teleconnection ( actual patterns being a composite of MANY interacting factors ).
AO
( Arctic Oscillation )
Winter 2011-12 featured an anomalously strong stratospheric and tropospheric polar vortex that acted to drive a strong +AO ( positive phase of the Arctic Oscillation teleconnection ).
November to April
500 MB Geopotential Height
Arctic Oscillation & Climate Correlations
Running longer term reanalysis it is not surprising to find that AO has positive correlations to 500 MB heights during the orographic forcing season, of November-April, from the eastern USA into western Europe.
The above map suggesting that a AO phase has highest positive correlations to 500 MB heights across the region of the southern Appalachians and Carolinas of the eastern USA.
The stronger the Polar Vortex ( the lower its heights ) the higher ( implied warmer ) mean heights become at lower latitudes during a +AO phase in general observation.
1976 to 2012
Arctic Oscillation Index Values
NAO
( North Atlantic Oscillation )
November to April
500 MB Geopotential Height
North Atlantic Oscillation & Climate Correlations
NAO phases have a even more expansive impact upon central-eastern portions of the USA, with positive correlations to 500 MB heights during the November-April period of orographic forcing.
Negative phases of both the AO and NAO favor negative 500 MB geopotential height patterns, in keeping with these positive correlations, across the central-eastern USA and western Europe ( i.e., -AO and -NAO phases favor, or teleconnect to, lower 500 MB heights and colder mean climatological conditions ).
1976 to 2012
North Atlantic Oscillation Index Values
State Climate Office of North Carolina
Positional Effects Of North Atlantic Oscillation
PNA
( Pacific North American Oscillation )
November to April
500 MB Geopotential Height
Pacific North American Oscillation
1976 to 2012
Pacific North American Index Values
Though this is only mid-September, the current setting is beginning to look very much like the longer term reanalysis for +PNA teleconnections observed during winter.
September 16, 2012 at 8:00 PM
European Model 500 MB Height Anomaly
PDO
( Pacific Decadal Oscillation )
November to April
500 MB Geopotential Height
Pacific Decadal Oscillation & Climate Correlations
PDO phases also have negative correlations to 500 MB heights across the southeastern USA, with a
-PDO ( cool phase ) possessing a correlation to higher 500 MB heights and a +PDO ( warm phase ) having a correlation to lower 500 MB heights.
December to February
500 MB Geopotential Height
Pacific Decadal Oscillation & Climate Correlations
Negative correlations to PDO phases show a stronger signal over the southeastern USA during December-February of meteorological winter.
The Pacific Decadal Oscillation ( PDO )
1976 to 2012
Pacific Decadal Oscillation Index Values
PDO Index Values ( 1948 to 2012 )
MEI
( Multivariate El Nino Southern Oscillation Index )
November to April
500 MB Geopotential Height
Multivariate ENSO Index & Climate Correlations
MEI values plotted graphically show positive ( red ) and negative ( blue ) oscillations between El Nino and La Nina events, respectively, through time.
Multivariate ENSO Index ( MEI )
1976 to 2012
Multivariate ENSO Index Values ( Recent )
Extended Multivariate ENSO Index ( MEI )
Nino 1+2 Region
( ENSO Correlations - Eastern Pacific )
December to February
500 MB Geopotential Height
Nino 1+2 Region & Climate Correlations
Breaking ENSO down by Pacific Ocean region during meteorological winter finds that correlations depend upon where it is based in the equatorial Pacific, with the ENSO 1+2 region having neutral to positive correlations from the Mountain Empire northward across the USA in contrast to negative correlations displayed by ENSO regions 3.4 and 4.
Studies have led to this generalized conclusion:
+ENSO forcing from eastern Pacific based El Nino events tends to favor warmer than average winter conditions
( higher 500 MB heights ) in the eastern United States and western Europe.
+ENSO forcing from central-western Pacific based
El Nino events tends to favor colder than average winter conditions ( lower 500 MB heights ) in the eastern USA and western Europe.
Central Pacific El Nino As Subtropical Bridge
SOI
( Southern Oscillation Index )
November to April
500 MB Geopotential Height
Southern Oscillation Index & Climate Correlations
The more traditional SOI Index possesses positive correlations to 500 MB geopotential heights across the southern half of the USA, with -SOI values
( El Nino ) correlating to lower heights and +SOI values ( La Nina ) correlating to higher heights.
1976 to 2012
Southern Oscillation Index Chart Of Values
NOI
( Northern Oscillation Index )
November to April
500 MB Geopotential Height
Northern Oscillation Index & Climate Correlations
There is an extratropical based SOI that is part of a new index called the NOI ( Northern Oscillation Index ) which shows stronger positive correlations to 500 MB geopotential heights, with centers located over the eastern Pacific Ocean and Gulf of Mexico.
1976 to 2007
Northern Oscillation Index Values
The Northern Oscillation Index ( NOI )
Note the extreme negative values observed on this index during the strongest +ENSO ( El Nino ) events of 1982-83 and 1997-98.
AMO
( Atlantic Multidecadal Oscillation )
November to April
500 MB Geopotential Height
Atlantic Multidecadal Oscillation & Climate Correlations
Atlantic Multidecadal Oscillation Page
AMO is a mode of natural variability in the North Atlantic Ocean sea surface temperature field.
Although the AMO displays little direct correlation to the southern Appalachians, it has significant positive correlations with the Hudson Bay and Greenland region to make it indirectly important over the long time spans in which phases run.
AMO Index Values ( Unsmoothed )
WHWP
( Western Hemisphere Warm Pool )
November to April
500 MB Geopotential Height
Western Hemisphere Warm Pool & Correlations
Seasonal correlations of 500 MB geopotential height with WHWP display patterns analogous to MEI across the Northern Hemisphere, with at least partial overlap of other teleconnections like PDO.
WHWP Index Values ( 1948 to 2012 )
MJO
( Madden-Julian Oscillation )
MJO Index ( 1997 to Present )
MJO Update - September 17, 2012 - CPC & NCEP
MJO is the dominant mode of short-period variability in the tropical atmosphere of planet Earth, featuring deep convective interactions between the mesoscale and planetary-scale waves. It is a very complex forcing that remains difficult for even the most sophisticated computer models to capture, let alone predict at extended ranges.
Madden-Julian Oscillation ( Chidong Zhang ) PDF
Capturing MJO is more than just a modeling problem
as understanding its convective pulses is theoretically difficult to explain. This remain an important area of study given its likely positive feedback with ENSO and subsequent linkage to other global-scale forcings.
Daily MJO Indices - Climate Prediction Center
MJO Correlations & Anomalies - CPC
QBO
( Quasi-biennial Oscillation )
November to April
500 MB Geopotential Height
Quasi-biennial Oscillation & Climate Correlations
QBO produces a cyclic variation in zonal winds of the tropical stratosphere with easterly and westerly flow fields having phase periods of approximately 27-28 months ( i.e., about every 27 months winds change direction in the tropical stratosphere via a top-bottom process ).
There are general positive correlations to changes in 500 MB heights across the United States and northern Atlantic with changes in QBO phases.
An easterly ( negative ) QBO phase tends to be associated with a weaker Polar Vortex while +QBO phases favor a strengthening of the Polar Vortex
( Stratospheric feeding into Tropospheric ).
Sunspots, The QBO, and Northern Hemisphere Stratosphere
1976 to 2012
Quasi-biennial Oscillation Index Values
QBO Index Values - NOAA
GLAAM
( Globally Averaged Angular Momentum )
November to April
850 MB Zonal Winds
Averaged Angular Momentum & Climate Correlations
Globally Averaged Angular Momentum ( GLAAM ) possesses strong negative correlations across much of the United States to 850 MB and 300 MB zonal wind fields, especially from the Rockies to the Appalachians, to illustrate that frictional effects are removing angular momentum where surface westerlies prevail ( sink region for atmospheric angular momentum ).
Surface stresses directed against surface winds are counted as positive in the region of mean easterlies which act as an atmospheric source region for global angular momentum, thus the positive correlations to 850-300 MB zonal wind fields displayed across tropical latitudes.
Note distinct poleward tilting with height from 850 to 300 MB of strongest negative correlations. This is driven by mean preferred SW to NE axial tilts of quasihorizontal eddies which act as the dominant transport mechanism of westerly angular momentum in middle latitudes.
GLAAM Index Values
NH Snow Area
( Northern Hemisphere Snowpack Area )
November to April
500 MB Geopotential Height
Northern Hemisphere Snow Area & Correlations
When it comes to North American snow cover its a no brainer that snowpack is negatively correlated to 500 MB geopotential heights across the USA, since as snowpack increases there is natural tendency for heights to become lower and for them to rise higher as it decreases in extent.
The implied and actual observed tendencies being for colder conditions with snow cover and milder conditions without it ( of course ).
Rutgers University data indicated that Summer 2012 had the least North American coverage of snow and ice on observed record ( mean for the
3-month season of June-August ).
January 2010 to August 2012
Monthly Snow Area Ranking - Northern Hemisphere
Arctic Sea Ice News & Analysis
Thoughts to be considered in this world of mass media bias.
There are many other climate forcings
( teleconnections ) not listed.
The analogy I like to use is that each major forcing can be thought of as a pebble dropped into a pond, which generates waves that ripple outward over time to impact locations in the pond far removed from the pebble itself ( and it's point of impact ).
When more than one pebble is dropped into the pond, as when multiple climate forcings are running at the same time, waves rippling outward from their source areas ( points of initial impact ) must interact in either constructive ways to make a given forcing stronger or destructive ways to make a given forcing weaker over any particular region of interest within the pond ( i.e., the atmosphere ).
Purely wave mathematics made simple!
In reality, of course, its much more complex with intimate couplings between various layers of the atmosphere internally as well as externally such that a summation of known teleconnections and their climatic correlations will not result in a consistent product but rather a unique product for any given place in space and time ( due to the non-linear nature of this system ).
While knowledge is increasing and forecasts are made for the upcoming seasons, often using pretty "analog" graphics of past seasons, the final reality will be a new and unqiue product to reinforce the most consistent and known factor of the climatic system...CHANGE!
September 16, 2012
Before The Autumn Storm - Wise County, Virginia
Appalachian Highland Colors Signal A Change
The arrival of this front was captured by the video camera of Wayne & Genevie Riner on Long Ridge.
Time Series Of Frontal Band
Click Consecutively On Images For Motion
Long Ridge At 12:32 PM - September 8, 2012
Long Ridge At 12:35 PM - September 8, 2012
Long Ridge At 12:39 PM - September 8, 2012
Long Ridge At 12:40 PM - September 8, 2012
Long Ridge At 12:40 PM - September 8, 2012
Long Ridge At 12:46 PM - September 8, 2012
Long Ridge At 12:47 PM - September 8, 2012
Long Ridge At 12:48 PM - September 8, 2012
Long Ridge At 12:49 PM - September 8, 2012
Long Ridge At 12:51 PM - September 8, 2012
Long Ridge At 12:56 PM - September 8, 2012
Long Ridge At 12:57 PM - September 8, 2012
Clearing skies into September 9 allowed temps to drop into the low-mid 40s amid higher mountain valleys, above 2500 feet elevation, from the
High Knob Massif to Burkes Garden.
Meanwhile, dense fog formed across the lower terrain with a distinct inversion layer developing within the Clinch, Powell, Holston, Russell Fork, and Cumberland river basins.
Photographer Roddy Addington was waiting atop Birch Knob of Pine Mountain, on the Virginia-Kentucky stateline, to capture this first crisp sunrise of Autumn 2012.
Awesome Morning Sunrise
Birch Knob of Pine Mountain
September 9, 2012
Cumberland Overthrust Block
Above Fog Layer of Morning Inversion
Photograph by Roddy Addington - © All Rights Reserved.
The Tavern On Main in Wise will host a gallery of Roddy Addington photography during the month of November. Everyone is invited!
Top Of Morning Inversion Layer
Sunrise Above A Sea Of Turbulent Waves
Photograph by Roddy Addington - © All Rights Reserved.
Striking Colors Of Morning Sunrise
Photograph by Roddy Addington - © All Rights Reserved.
At One In Space & Time - Majestic Colorations
Photograph by Roddy Addington - © All Rights Reserved.
Highland Fields Emerge Above Wavy Fog
Photograph by Roddy Addington - © All Rights Reserved.
NASA Visible Images
The View From Above
September 9, 2012
NASA Visible Image At 1245 UTC ( 8:45 AM )
NASA Visible Image At 1301 UTC ( 9:01 AM )
NASA Visible Image At 1316 UTC ( 9:16 AM )
Fog dissipated quickly with vertical mixing through mid-morning in the Russell Fork and Levisa Fork basins, but was slower to evaporate amid the Clinch and Holston watersheds of the Upper Tennessee River Basin.
NASA Visible Image At 1345 UTC ( 9:45 AM )
Observe how the inverted V-shaped fog bank in Powell Valley of the High Knob Massif dissipated between 10:01 AM and 10:31 AM ( clear skies above had generated much cooler conditions in high valleys from Big Cherry Lake to High Knob Lake and The Glades to Bark Camp Lake ).
NASA Visible Image At 1401 UTC ( 10:01 AM )
NASA Visible Image At 1431 UTC ( 10:31 AM )
NASA Visible Image At 1445 UTC ( 10:45 AM )
Climate Statistics
September 1-15, 2012
( Lower Elevations of Russell Fork Basin )
Clintwood 1 W - Elevation 1560 feet
Average Daily MAX: 78.3 degrees
Average Daily MIN: 57.3 degrees
MEAN: 67.8 degrees
Highest Temperature: 86 degrees
Lowest Temperature: 45 degrees
Rainfall: 1.06"
2012 Precipitation: 32.21"
( Northern Base of High Knob Massif )
City of Norton - Elevation 2141 feet
Average Daily MAX: 77.9 degrees
Average Daily MIN: 54.7 degrees
MEAN: 66.3 degrees
Highest Temperature: 85 degrees
Lowest Temperature: 42 degrees
Rainfall: 1.68"
2012 Precipitation: 50.54"
( Along the Tennessee Valley Divide )
Nora 4 SSE - Elevation 2650 feet
Average Daily MAX: 77.0 degrees
Average Daily MIN: 60.3 degrees
MEAN: 68.6 degrees
Highest Temperature: 83 degrees
Lowest Temperature: 51 degrees
Rainfall: 1.04"
2012 Precipitation: 31.82"
In the High Knob Massif the first half of September featured mean maximums in the 60s to lower 70s at highest elevations by day, with 50 to 55 degree average lows at night ( the coolest night featuring 30s to lower 40s in high valleys on September 11 ).
September 13, 2012
Majestic Evening Colors
Sunset Along The Tennessee Valley Divide
Photograph by Wayne Riner - © All Rights Reserved.
Wayne Riner Photograph Thoughts...
"Suddenly the sky to the west was bright with color while the rest of the area was dark. At this time in the evening a few birds sang."
Global Connections
Major Autumn Storm Expected
September 17-18, 2012
A major league autumn storm system is expected to impact the Appalachians during September 17-18 as an unseasonably strong trough digs south out of Canada to trigger an anomalous, early season synoptic-scale rainfall event.
A forecast model spread of 1.00" to 5.00" of rainfall is being predicted across the southern Appalachians during the September 17-18 period. Folks living along streams and in poor drainage, flood prone locations should monitor water levels closely later Monday and Tuesday as rain increases in both amount & intensity.
September 15, 2012
European Model Analysis At 8:00 PM
September 16, 2012
European Model Forecast At 8:00 PM
September 17, 2012
European Model Forecast At 8:00 PM
September 18, 2012
European Model Forecast At 8:00 PM
While above charts are subject to change with new runs of the model, this scenario has been very consistent for consecutive days on ECMWF forecasts.
A deep 984 MB ( 29.06" ) low blasting the Aleutians, in the Gulf of Alaska, is helping drive this process by buckling the Polar Jet and aiding formation of a +PNA ridge complex along the western coastlines of North America.
September 15, 2012
Pacific Surface Analysis At 21:05 UTC
This is part of a continuing hemispheric pattern change that started September 8-9 and kicks into high gear during the upcoming 5-10 day period as indicated by European Model 500 MB Height Anomaly forecasts.
September 15, 2012 at 8:00 PM
European Model 500 MB Height Anomaly
September 18, 2012 at 8:00 PM
European Model Forecasted 500 MB Height Anomaly
September 20, 2012 at 8:00 PM
European Model Forecasted 500 MB Height Anomaly
September 22, 2012 at 8:00 PM
European Model Forecasted 500 MB Height Anomaly
September 25, 2012 at 8:00 PM
European Model Forecasted 500 MB Height Anomaly
The strong storm system and chilly air dump that will send temperatures plunging across western slopes of the Appalachians late on September 18 into September 19 will give way to warm air transport ahead of another, even stronger cold front that currently looks to bring the coldest air mass into the region by the September 23-24 period ( with meridional flow and 500 MB anomalies ).
Part of the higher than average confidence in this forecast scenario rests in a Super Typhoon named Sanba and convection associated with the Madden-Julian Oscillation ( MJO ) that is in position to feed energy into the polar westerlies ( aiding amplification ).
September 13, 2012 at 0450 UTC
High Resolution NASA Visible - Super Typhoon Sanba
Anomalous sea surface temperatures across the Northern Pacific Ocean and the Northwest Atlantic are adding support and could be important factors heading into the upcoming cold season if they persist over time through coming weeks.
These circled anomalies have been more impressive than the weak, developing +ENSO ( El Nino ) that is indicated by warmer than average sea surface temps along the Equator west of South America.
Warmer than average sea surface temperatures
( SST ) across the North Pacific are associated with a cool phase of the Pacific Decadal Oscillation, or
-PDO teleconnection, which climate correlations tend to show are opposed to +ENSO phases ( * ).
A -PDO added to -ENSO ( La Nina ) and +PDO added to a +ENSO ( El Nino ) would tend to reinforce ENSO forcing
( wave trains interact in constructive ways ).
A -PDO added to +ENSO and +PDO added to a -ENSO tends to oppose ENSO forcing ( wave trains from their forcing tend to interact in destructive ways to reduce their mean climatological influences on the eastern USA ).
*Current trends are for a central-west based +ENSO ( El Nino ) during Winter 2012-13 which would favor colder than average conditions across the eastern USA and western Europe. Will this tendency be canceled or overwhelmed by a -PDO phase, and will anomalously warm SST remain over the northwestern Atlantic to tip the scales back toward a colder eastern USA? Stay tuned.
( Many other factors will also be at play ).
Teleconnection Forecasts
( Short-Term Outlook )
Climate anomalies that force weather changes in places far removed from where they occur are known as teleconnections.
Many are defined and used to anticipate weather changes, while many more teleconnections remain hidden amid the complexity of this climatic system ( a composite system of all living and non-living things in space and time ).
-NAO and ++PNA
Recent NAO History & Forecast
Recent PNA History & Forecast
A negative phase of North Atlantic Oscillation
( -NAO ), and developing Greenland Block, is coupling with a very strong positive phase of the Pacific North American teleconnection ( ++PNA ) to support wet, much colder conditions across the Appalachians during this week of September 17-22 ( and perhaps for the remainder of this month ).
Recent AO History & Forecast
EPO Forecast
Negative phases of the Arctic Oscillation ( -AO ) and Eastern Pacific Oscillation ( -EPO ) also support the upcoming change to stormy, colder conditions in the eastern USA.
Global Teleconnections
And Climate Correlations
An Orographic Forcing Season Perspective
While the southern Appalachians have four celebrated seasons with distinct and dramatic landscape changes, from a climatology perspective there are only two that rule!
1 ). The Orographic Forcing Season
*November-April
2 ). The Convective Season
*May-October
*May and October are often months of transition, and depending upon the year can be dominated by either climatic mode. More often than not, however, they are ruled by a mixture of both forcing and convective events. While either can occur during any month, orographic forcing is most likely the dominant mode observed during the November to April period.
When north to south temperature gradients develop across North America the atmosphere becomes more baroclinic ( density of the air is a function of both pressure and temperature ), such that synoptic-scale storm systems arise with winds that push against the topography.
In a most simplistic way, this leads to orographic forcing with its upsloping and downsloping.
In reality, orographic forcing is MUCH more complex and involves a host of parameters that dictate the nature of both daily weather conditions and longer term climate in locations resting within the mountains, as well as up and down stream of air flow trajectories interacting with them at different levels ( ** ).
**This includes a myriad of orographically generated waves whose amplitudes occasionally exceed their wavelengths to allow wave breaking ( i.e., overturning like ocean waves rolling toward a beach where frictional drag at the bottom, beneath the water, is increasingly "felt" by the waves to cause them to roll over and expend their transported momentum and energy ).
Note that the following teleconnection patterns could be looked at using different parameters from the 500 MB geopotential height field, but given general "smoothing" that occurs at 500 MB it is suitable for basic statistical correlations of mean climatic tendencies.
Maps below DO NOT indicate actual height departures and DO NOT imply strict causation by just a single teleconnection ( actual patterns being a composite of MANY interacting factors ).
AO
( Arctic Oscillation )
Winter 2011-12 featured an anomalously strong stratospheric and tropospheric polar vortex that acted to drive a strong +AO ( positive phase of the Arctic Oscillation teleconnection ).
November to April
500 MB Geopotential Height
Arctic Oscillation & Climate Correlations
Running longer term reanalysis it is not surprising to find that AO has positive correlations to 500 MB heights during the orographic forcing season, of November-April, from the eastern USA into western Europe.
The above map suggesting that a AO phase has highest positive correlations to 500 MB heights across the region of the southern Appalachians and Carolinas of the eastern USA.
The stronger the Polar Vortex ( the lower its heights ) the higher ( implied warmer ) mean heights become at lower latitudes during a +AO phase in general observation.
1976 to 2012
Arctic Oscillation Index Values
Judah Cohen PDF
NAO
( North Atlantic Oscillation )
November to April
500 MB Geopotential Height
North Atlantic Oscillation & Climate Correlations
NAO phases have a even more expansive impact upon central-eastern portions of the USA, with positive correlations to 500 MB heights during the November-April period of orographic forcing.
Negative phases of both the AO and NAO favor negative 500 MB geopotential height patterns, in keeping with these positive correlations, across the central-eastern USA and western Europe ( i.e., -AO and -NAO phases favor, or teleconnect to, lower 500 MB heights and colder mean climatological conditions ).
1976 to 2012
North Atlantic Oscillation Index Values
courtesy of
The position of the -NAO anomaly is important, with those centered southwest of an axial line drawn northwest to southeast through Greenland being WEST-BASED and those northeast of that imaginary line being EAST-BASED in nature.
The eastern USA is impacted most significantly
( in terms of cold ) by a west-based -NAO.
State Climate Office of North Carolina
Positional Effects Of North Atlantic Oscillation
PNA
( Pacific North American Oscillation )
November to April
500 MB Geopotential Height
Pacific North American Oscillation
A PNA teleconnection pattern possesses negative correlations to 500 MB heights across much of the southern and eastern USA, implying that +PNA phases correlate to lower 500 MB geopotential heights while -PNA phases correlate to higher
500 MB heights.
1976 to 2012
Pacific North American Index Values
Though this is only mid-September, the current setting is beginning to look very much like the longer term reanalysis for +PNA teleconnections observed during winter.
September 16, 2012 at 8:00 PM
European Model 500 MB Height Anomaly
PDO
( Pacific Decadal Oscillation )
November to April
500 MB Geopotential Height
Pacific Decadal Oscillation & Climate Correlations
PDO phases also have negative correlations to 500 MB heights across the southeastern USA, with a
-PDO ( cool phase ) possessing a correlation to higher 500 MB heights and a +PDO ( warm phase ) having a correlation to lower 500 MB heights.
December to February
500 MB Geopotential Height
Pacific Decadal Oscillation & Climate Correlations
Negative correlations to PDO phases show a stronger signal over the southeastern USA during December-February of meteorological winter.
The Pacific Decadal Oscillation ( PDO )
1976 to 2012
Pacific Decadal Oscillation Index Values
MEI
( Multivariate El Nino Southern Oscillation Index )
November to April
500 MB Geopotential Height
Multivariate ENSO Index & Climate Correlations
MEI incorporates multiple parameters in the coupled ocean-atmosphere system to depict ENSO phases, with long term reanalysis showing negative correlations to 500 MB geopotential heights across the southern half of the United States.
+MEI phases ( El Nino ) correlate to lower 500 MB heights across the southern USA while -MEI phases ( La Nina ) correlate to higher heights.
MEI values plotted graphically show positive ( red ) and negative ( blue ) oscillations between El Nino and La Nina events, respectively, through time.
1976 to 2012
Multivariate ENSO Index Values ( Recent )
Extended Multivariate ENSO Index
Nino 1+2 Region
( ENSO Correlations - Eastern Pacific )
December to February
500 MB Geopotential Height
Nino 1+2 Region & Climate Correlations
Nino 3.4 Region
( ENSO Correlations - Central Pacific )
December to February
500 MB Geopotential Height
Nino 3.4 Region & Climate Correlations
Nino 4 Region
( ENSO Correlations - Western Pacific )
December to February
500 MB Geopotential Height
Nino 4 Region & Climate Correlations
Breaking ENSO down by Pacific Ocean region during meteorological winter finds that correlations depend upon where it is based in the equatorial Pacific, with the ENSO 1+2 region having neutral to positive correlations from the Mountain Empire northward across the USA in contrast to negative correlations displayed by ENSO regions 3.4 and 4.
Studies have led to this generalized conclusion:
+ENSO forcing from eastern Pacific based El Nino events tends to favor warmer than average winter conditions
( higher 500 MB heights ) in the eastern United States and western Europe.
+ENSO forcing from central-western Pacific based
El Nino events tends to favor colder than average winter conditions ( lower 500 MB heights ) in the eastern USA and western Europe.
Central Pacific El Nino As Subtropical Bridge
SOI
( Southern Oscillation Index )
November to April
500 MB Geopotential Height
Southern Oscillation Index & Climate Correlations
The more traditional SOI Index possesses positive correlations to 500 MB geopotential heights across the southern half of the USA, with -SOI values
( El Nino ) correlating to lower heights and +SOI values ( La Nina ) correlating to higher heights.
1976 to 2012
Southern Oscillation Index Chart Of Values
NOI
( Northern Oscillation Index )
November to April
500 MB Geopotential Height
Northern Oscillation Index & Climate Correlations
There is an extratropical based SOI that is part of a new index called the NOI ( Northern Oscillation Index ) which shows stronger positive correlations to 500 MB geopotential heights, with centers located over the eastern Pacific Ocean and Gulf of Mexico.
1976 to 2007
Northern Oscillation Index Values
The Northern Oscillation Index ( NOI )
Note the extreme negative values observed on this index during the strongest +ENSO ( El Nino ) events of 1982-83 and 1997-98.
AMO
( Atlantic Multidecadal Oscillation )
November to April
500 MB Geopotential Height
Atlantic Multidecadal Oscillation & Climate Correlations
Atlantic Multidecadal Oscillation Page
AMO is a mode of natural variability in the North Atlantic Ocean sea surface temperature field.
Although the AMO displays little direct correlation to the southern Appalachians, it has significant positive correlations with the Hudson Bay and Greenland region to make it indirectly important over the long time spans in which phases run.
AMO Index Values ( Unsmoothed )
WHWP
( Western Hemisphere Warm Pool )
November to April
500 MB Geopotential Height
Western Hemisphere Warm Pool & Correlations
Anomalies of the sea surface area of the Atlantic and North Pacific with temperatures warmer than 28.5 degrees Celsius make up the Western Hemispheric Warm Pool ( WHWP ).
Seasonal correlations of 500 MB geopotential height with WHWP display patterns analogous to MEI across the Northern Hemisphere, with at least partial overlap of other teleconnections like PDO.
WHWP Index Values ( 1948 to 2012 )
MJO
( Madden-Julian Oscillation )
MJO Index ( 1997 to Present )
MJO is the dominant mode of short-period variability in the tropical atmosphere of planet Earth, featuring deep convective interactions between the mesoscale and planetary-scale waves. It is a very complex forcing that remains difficult for even the most sophisticated computer models to capture, let alone predict at extended ranges.
Madden-Julian Oscillation ( Chidong Zhang ) PDF
Capturing MJO is more than just a modeling problem
as understanding its convective pulses is theoretically difficult to explain. This remain an important area of study given its likely positive feedback with ENSO and subsequent linkage to other global-scale forcings.
Daily MJO Indices - Climate Prediction Center
MJO Correlations & Anomalies - CPC
QBO
( Quasi-biennial Oscillation )
November to April
500 MB Geopotential Height
Quasi-biennial Oscillation & Climate Correlations
QBO produces a cyclic variation in zonal winds of the tropical stratosphere with easterly and westerly flow fields having phase periods of approximately 27-28 months ( i.e., about every 27 months winds change direction in the tropical stratosphere via a top-bottom process ).
There are general positive correlations to changes in 500 MB heights across the United States and northern Atlantic with changes in QBO phases.
An easterly ( negative ) QBO phase tends to be associated with a weaker Polar Vortex while +QBO phases favor a strengthening of the Polar Vortex
( Stratospheric feeding into Tropospheric ).
Sunspots, The QBO, and Northern Hemisphere Stratosphere
1976 to 2012
Quasi-biennial Oscillation Index Values
GLAAM
( Globally Averaged Angular Momentum )
November to April
850 MB Zonal Winds
Averaged Angular Momentum & Climate Correlations
November to April
300 MB Zonal Winds
Averaged Angular Momentum & Climate Correlations
Surface stresses directed against surface winds are counted as positive in the region of mean easterlies which act as an atmospheric source region for global angular momentum, thus the positive correlations to 850-300 MB zonal wind fields displayed across tropical latitudes.
Note distinct poleward tilting with height from 850 to 300 MB of strongest negative correlations. This is driven by mean preferred SW to NE axial tilts of quasihorizontal eddies which act as the dominant transport mechanism of westerly angular momentum in middle latitudes.
GLAAM Index Values
Mountain torque is a critical part of GLAAM and plays a vital role in many global teleconnection patterns via forcing, wave transport and other processes such as wave breaking.
Additional Wave Information Examples:
( In the Equatorial Middle Atmosphere )
( Good Guide To Basic Waves )
NH Snow Area
( Northern Hemisphere Snowpack Area )
November to April
500 MB Geopotential Height
Northern Hemisphere Snow Area & Correlations
When it comes to North American snow cover its a no brainer that snowpack is negatively correlated to 500 MB geopotential heights across the USA, since as snowpack increases there is natural tendency for heights to become lower and for them to rise higher as it decreases in extent.
The implied and actual observed tendencies being for colder conditions with snow cover and milder conditions without it ( of course ).
Rutgers University data indicated that Summer 2012 had the least North American coverage of snow and ice on observed record ( mean for the
3-month season of June-August ).
January 2010 to August 2012
Arctic Sea Ice News & Analysis
AAO
( Antarctica Oscillation )
AAO Index Values
Although it may not be considered by most living in the Northern Hemisphere, given connections of global climate it really should be no surprise that evidence points to a climatic connection between Antarctica and the Northern Hemisphere.
Zonally Averaged Zonal Wind
"It is found that during boreal winter,
a positive (negative) phase of the AAO is associated with anomalous easterlies (westerlies) in middle-low latitudes (~30–40 N) and anomalous westerlies (easterlies) in middle-high latitudes (~45–65 N) of the upper troposphere about 25–40 days later."
Signature of the AAO in the northern hemisphere
Meteorol Atmos Phys (2009) 105:55–67
It should also be pointed out that the record of Antarctic Sea Ice has shown a steady but significant increase over time during its period of observation.
Monthly Deviations and Trend Of Antarctic Sea Ice
"When examined through the annual cycle over the
32-yr period 1979–2010, the Southern Hemisphere sea ice cover as a whole experienced positive ice extent trends in every month, ranging in magnitude from a low of 9100 ± 6300 km2 yr−1 in February to a high of 24 700 ± 10 000 km2 yr−1 in May."
Antarctic sea ice variability and trends, 1979–2010
The Cryosphere, 6, 871–880, 2012
Since Antarctica is MUCH bigger than the Arctic,
it is interesting to think that globally this positive INCREASE in ice across Antarctica has acted to balance or even exceed that lost in the Arctic with changes acting to influence weather patterns across the Northern Hemisphere
( forcing from both poles )!
Thoughts to be considered in this world of mass media bias.
( teleconnections ) not listed.
The analogy I like to use is that each major forcing can be thought of as a pebble dropped into a pond, which generates waves that ripple outward over time to impact locations in the pond far removed from the pebble itself ( and it's point of impact ).
When more than one pebble is dropped into the pond, as when multiple climate forcings are running at the same time, waves rippling outward from their source areas ( points of initial impact ) must interact in either constructive ways to make a given forcing stronger or destructive ways to make a given forcing weaker over any particular region of interest within the pond ( i.e., the atmosphere ).
Purely wave mathematics made simple!
In reality, of course, its much more complex with intimate couplings between various layers of the atmosphere internally as well as externally such that a summation of known teleconnections and their climatic correlations will not result in a consistent product but rather a unique product for any given place in space and time ( due to the non-linear nature of this system ).
While knowledge is increasing and forecasts are made for the upcoming seasons, often using pretty "analog" graphics of past seasons, the final reality will be a new and unqiue product to reinforce the most consistent and known factor of the climatic system...CHANGE!
September 16, 2012
Before The Autumn Storm - Wise County, Virginia
Appalachian Highland Colors Signal A Change
Photograph by Roddy Addington - © All Rights Reserved.
Autumn Storm Update
( As of September 19, 2012 )
A general 3.00" to 6.00" of rain fell along the
High Knob Landform during this storm episode, with 3.50" to 4.00"+ observed from Norton & Coeburn across the High Knob Massif in southern Wise, northern Scott, and northeastern Lee counties of southwestern Virginia ( # ).
( Northern base of High Knob Massif )
City of Norton Water Plant
Observer - Tommy Roberts & Staff
Elevation 2342 feet
Storm Rainfall Total: 3.63"
September Total: 5.32"
Total Since July 1: 24.13"
2012 Total: 54.18"
12-Month Total: 75.38"
Storm Total of 4.65" in Little Stone Mountain Gap
( 6.60" in September - Near Powell Valley Overlook )
( Upper Little Stony Creek - Burns Creek basins )
Robinson Knob of High Knob Massif
Observer - Otis & Nancy Ward
Elevation 3240 feet
Storm Rainfall Total: 4.08"
September Total: 5.59"
Total Since July 1: 27.18"
2012 Total: 55.41" ( M )
12-Month Total: 78.23" ( M )
( M ) - Indicates missing moisture in deeper falls of winter snow.
( South Fork Gorge of High Knob Massif )
Big Stone Gap Water Plant
Observer - Gary Hampton & Staff
Elevation 1960 feet
Storm Rainfall Total: 3.68"
September Total: 5.97"
Total Since July 1: 23.90"
2012 Total: 50.95"
12-Month Total: 70.69"
Storm Rainfall Total of 4.00" at Big Cherry Dam
( 6.07" in September )
#The Heaviest 5.00" to 6.00" amounts fell locally across the southwestern end of the High Knob Landform within the Cumberland Gap to Norris Lake and I-75 corridor.
September 9, 2012
Early Autumn Sun Rays In Mountain Forest
Photograph by Roddy Addington - © All Rights Reserved.
A general 2.00" to 3.00"+ fell across the Russell Fork Basin during this storm episode ( north-northeast of the High Knob Landform ).
( Lower elevations of Russell Fork Basin )
Clintwood 1 W NWS Cooperative
Observer - Wayne Browning
Elevation 1560 feet
Storm Rainfall Total: 2.54"
September Total: 3.60"
Total Since July 1: 13.74"
2012 Total: 34.75"
12-Month Total: 49.11"
( Along the Tennessee Valley Divide )
Nora 4 SSE NWS Cooperative
Observer - Wayne & Genevie Riner
Elevation 2650 feet
Storm Rainfall Total: 3.30"
September Total: 4.34"
Total Since July 1: 11.98"
2012 Total: 35.12"
12-Month Total: 49.83"
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