Tuesday, November 17, 2009

Winter 2009-10: The Good, Bad, And UGLY


Wooly Bear Caterpillar ( Pyrrharctia isabella )
Photograph by Roddy Addington - © All Rights Reserved.

Unlike our beloved Wooly Bears, as captured above by my friend and photographer Roddy Addington, the road to predicting what the coming winter will be like is not pretty, cute, and cuddly.

It's pure-dee UGLY!

By the way, Wooly Bear Caterpillars ( Pyrrharctia isabella ) wonder how in the world they ever got caught up in this chaos?

Wooly Bears are the larval form of the Isabella Tiger Moth.  They emerge in autumn, just before winter, and are actually able to survive frigid conditions by producing a substance that essentially is a natural form of antifreeze!

They naturally vary in color from brown to black, with the banding taken to represent what the upcoming winter will be like being markers of age. 

[ To again be completely honest, it can be a BIT more complicated since their family of Arctiidae does ONLY contain 11,000+ known species across the planet...but I'm working an angle here, so hang with me! ].

Yes, indeed, youngsters tend to be mostly black and the older, mature elders of the species tend to be mostly brown.

The BANDING actually marks different instar stages, so that its indicative of age and maturity, not to future weather. 

YOU SILLY ole Homo sapiens sapiens!

Oh well, back to the drawing board!

Now this is where it get's kinda UGLY, because the simple, honest, and sincere truth is that NO ONE ALIVE today, nor any Super-MACHINE, can tell you what the upcoming winter will be like weeks, and dare we say months, in advance!!

Anyone can guess that it will be either GOOD or BAD ( depending upon your definition of such ), and be right 50 percent of the time ( like tossing a single, unbiased coin ).

Although many valient efforts are made, and some claim HIGH success rates, the real nitty-gritty of the UGLY is that important details of daily, weekly, and monthly weather variations are sorely lacking for specific locations where you and I live, work, and play.

[ A large-scale trend that might dominate a couple weeks, or a MONTH, is often easier to define in advance than are the daily details of short-term weather changes.  In fact, some interesting climate patterns have been found that are just as important to future winter conditions as are the ones driven by the well known ENSO ( El Nino & La Nina of the Southern Oscillation )  ].

WOW, I'm glad that I am no foreACTOR, I mean foreCASTER!

[ Sorry my weather BIZ friends ( used to be ), I just couldn't let that one pass!!! ].

Seriously, there are some very good forecasters who put in a great amount of time and effort to crank out winter predictions ( a few of which I will be linking to later for you to check ).

Meanwhile, we'll be looking at the GOOD and BAD of this chaotic situation!

GOOD News - Major Forcings
Identified ( at least SOME of THEM )!

Frosty Cold Morn - Powell Valley of High Knob Massif
Photograph by Roddy Addington - © All Rights Reserved.

Will the winter ahead feature more frosty cold mornings like captured by Roddy above, OR will it feature more dazzling WHITE mornings beneath a blanket of sparkling SNOW?

That is the BIG question which is ALWAYS numerial-UNO in the minds of both lovers of the "white stuff," and haters alike!

The Good News during 2009-10 is that there is a teleconnection running in which we know will have a major influence upon weather conditions.

It is the positive phase of ENSO, The El Nino-Southern Oscillation.

You see, El Nino is only the above "normal" warming of sea surface temperatures across the equatorial Pacific Ocean.  While that is indeed the real forcing factor, the positive phase of ENSO, of which El Nino episodes represent, is more than just oceanic warming!

During the 1920s, to present historical insight, a researcher by the name of Sir Gilbert Walker was in India trying to unravel the rather mysterious nature of the annual monsoon that is such a prominent feature of the Asian climate.

He observed that different seasons would produce monsoons of varying intensities.  Some seasons, for example, would bring great flooding, while others would produce so little rain that drought conditions would engulf the region.

These fluctuations could mean the difference between life and death for millions of people, such that the discovery of a way to predict monsoonal intensities would be, needless to say, of enormous value.

In his research Walker discovered what is known today as a

TELECONNECTION.

A teleconnection is where weather conditions occurring in one region on earth can force changes in another region FAR away.

Walker found that when sea level pressures are low, relative to average, in India and the western Pacific, they tend to be high, relative to average, across the central and eastern Pacific.

Likewise, when sea level pressures are high in India and adjacent regions of the western Pacific they tend to be low ( relative to average ) across the central and eastern Pacific.

Walker named these pressure swings the Southern Oscillation.

He had discovered an important piece of the puzzle that is so commonly called El Nino today!

Some 40 year later another researcher named Jacob Bjerknes became the first to make a connection between abnormal sea surface temperatures and the oscillations in pressure discovered by Walker.

He had discovered the oceanic forcing component called El Nino.

El Nino is spanish for the "Christ child."  Fishermen along the coastlines of Ecuador and Peru, in South America, originally began using the term to name a weak and unusually warm ocean current that would appear on an annual basis around the time of Christmas. 

During some years this warming would become strong, with significant and locally disastrous impacts upon both their fishing and the landscape ( it would stop the upwelling of cold waters and cause deadly flooding along the windward slopes of the Andes ).

But how can this be?

How can something like this, so FAR away, impact the High Knob Landform and southern Appalachians?


The FLUID Atmosphere

Looking from Pine Mountain toward High Knob Landform
Photograph by Roddy Addington - © All Rights Reserved.

[ When the ever present water vapor becomes visible in the atmosphere, as seen above, its wavy, fluid nature will eventually emerge, sometimes, in dramatic and breathtakingly stunning fashion ].

As I always teach, the KEY to obtaining an understanding for the workings of our amazing atmosphere are based upon its FLUID nature.  Mathematics are essential for a complete understanding, but anyone can learn by the way I teach from my research experience.

If you are not blessed enough to stand upon our high mountains and capture a scene so glorious as that which was documented by photographer Roddy Addington above, then go to the nearest lake or pond!

If you drop a pebble into a pond, waves ripple away from the point of impact.  If you drop two pebbles separated by a distance, the waves from each point of impact ripple outward and interact with each other in various and interesting ways!

Two waves approaching each other can either interact in a constructive way, and combine energies to form a larger wave with more total energy, or they can interact in a destructive way to cancel ( or partially cancel ) each other out ( dissipating their energies ).

A small pebble generates small rippling waves, while a large rock dropped into the water generates BIG waves.

And so it is with the fluid ATMOSPHERE.

On micro to meso scales, as illustrated by Roddy's photograph above, the fluid nature of the air around us is so VERY evident, energetic, and simply MAGICAL.

[ In the above photograph, taken on Pine Mountain and looking outward toward the High Knob Landform ( HKL ), sun exposed mountain slopes and the cool, foggy lower terrain acted to generate a vast array of rising and sinking waves, rolls, and other ripples along the surface of a morning inversion layer, revealing the truly dynamic nature of the air around us at all times ( its just not always so visibly gorgeous )].

On the SYNOPTIC or LARGE scale, the pebbles and rocks in question are all the forcing factors, like El Nino or ENSO, which perturb the fluid.

El Nino is able to perturb the atmosphere via the abnormal warming of the sea surface which initially generates a vast array of micro-turbulence that begins mixing and overturning air in contact with the air-sea interface.

In time, and with persistence of the temperature anomaly, this micro-turbulence grows exponentially in its scope and intensity, such that deep convection forms above the warmed ocean. 

Like a fire, which begins as a mere flicker and turns into a raging inferno, the influence of initial oceanic warming grows to influence the pressure patterns across the entire expanse of the equatorial Pacific, marking the formation of a positive phase of ENSO.

[ Its negative phase is called La Nina, in short-hand terminology, and marked by abnormally cold sea surface temperatures which generate opposite pressure oscillations across the Pacific Basin ].

In this way, ENSO can be thought of as a rock dropped into the water, with waves rippling outward from its point of impact ( the equatorial Pacific Ocean ) throughout the surrounding fluid ( global atmosphere ).

The communication of the ENSO influence beyond the immediate region of the air-sea interface depends upon the sensitivity of the atmosphere to changes in deep convection.

When ENSO is running, it subjects the atmosphere to constant forcing as its energy ripples away from the equator to interact in complex ways with a myriad of other oscillatory atmospheric disturbances.

Thus, ENSO is a TELECONNECTION, since from its point of impact, energy in the form of rippling waves moves outward to perturb the air in locations FAR, FAR away from where it began.

A WEAK ENSO of positive phase is analogous to dropping a small pebble into a pond.  It generates waves, but they are not nearly as STRONG nor as far reaching as those generated by bigger pebbles, and can therefore be more easily overcome or canceled by other waves originating from different "pebbles" in the pond.

A STRONG ENSO of positive phase is therefore analogous to dropping a BIG rock into a pond, with generation of significant waves that are far reaching and dominant in their influence over other waves rippling throughout the fluid atmosphere.

The above being a greatly OVER-SIMPLIFIED analogy in order to aid understanding.  Some of the true complexity will be noted subsequently.

Sea Surface Temperature Anomalies - November 15, 2009
Image courtesy of Unisys Weather

The above graphic illustrates the present sea surface temperature anomalies across the globe.

The zone inside the YELLOW outlines the critical El Nino warming region.  Other areas of abnormally cold sea surface temperatures ( inside the PURPLE ), south of the Gulf of Alaska and the rugged Newfoundland Coast, are also very important ( especially if they persist over time ).

The current positive phased ENSO is moderate to borderline strong, and models run by the Climate Prediction Center indicate that it will remain at least weak to moderate through the 2009-10 winter season.

Here is a higher resolution sea surface temp anomaly map, courtesy of NOAA Satellite and Information Service ( NESDIS ) and the National Climatic Data Center ( NCDC ), which compares present anomalies to that of the recent 1971-2000 mean or base period ( soon to be replaced by 1981-2010 means ).


Here is a link to watch it change over time, courtesy of NCDC & NOAA:

http://lwf.ncdc.noaa.gov/oa/climate/research/sst/ani-weekly.html

[ An interesting note, during El Nino episodes the length of a day actually increases by a tiny fraction since the associated stronger westerly winds pushing against the surfaces of Earth require that its rotation slow ever so slightly, in order to abide by the law of conservation of angular momentum.  This according to a NASA funded research project and David A. Salstein ].

Using my analogy above, EVERY major disturbance or variation in the global atmosphere can be modeled as a pebble or rock dropping into it's fluid, with resultant waves rippling outward from where they originate.

All the other identified teleconnections are therefore included, as well as such things as the pattern and deposition of winter snow cover at mid to high latitudes.

A few other important teleconnections include:

AO - The Arctic Oscillation

NAO - The North Atlantic Oscillation

PNA - The Pacific North American Oscillation

EPO - The Eastern Pacific Oscillation

WPO - The Western Pacific Oscillation

MJO - The Madden-Julian Oscillation

PDO - The Pacific Decadal Oscillation

NPO - The North Pacific Oscillation

AAO - The Antarctic Oscillation

QBO - The Quasi-biennial Oscillation .

All of these teleconnections plus MANY more that are minor, or simply NOT yet known, are pebbles and rocks dropping into the fluid atmosphere.  Each one has positive, neutral, and negative phases, and each one impacts the atmosphere via waves rippling outward from their regions of origin.

ADD in the following facts:

1 ).  The Earth spins at 1038.0 miles per hour at the equator .

2 ).  The Earth's orbital speed around the sun is approximately 66.6 miles per hour.

3 ).  The Earth is frozen at the poles.

4 ).  The Earth is heated at the equator.

5 ).  The Earth's surface is 71 percent covered by water.

6 ).  The Earth has many mountain ranges that extend above its PBL ( planetary boundary layer ).

7 ).  The surfaces are Earth are CONSTANTLY being perturbed and changed by mankind, in addition to mother nature.

[ The surfaces of Earth act like synapses of neurons in the brain, or the interfaces of a computer, where information is selectively relayed to all other parts of the system.

Mankind, of all possible species alive today, possesses the ability to impact Earth most through changes he makes in its surfaces ( thus disrupting the natural communication and flow of diverse forms of energy within the climatic system that by definition includes the biosphere )].


The Complexity of the Problem

The complexity of the problem facing a super-computer, not to mention a human forecaster, is to take the positive phase of ENSO and to combine it with ALL of the other teleconnections and factors listed above.

That roughly ( very roughly ) covers the LARGE or Synoptic-scale.

Now add in the vast array of regional to local scale forcing factors, such as the orographics of the High Knob Landform, to the above mixture, shake it up, and what do you GET??

You get back to the pure-dee UGLY in which we started!

Hey, I thought this was the GOOD NEWS section?

Well, there is HOPE.  All is not lost.  Amid this resultant chaos, of which the above generates, there is some trends which can be assimilated into at least a bit of ORDER.


What We Know:
Thank God for Climatology

Yes, indeed, thank the good Lord above for daily weather observers, researchers, and climatologists who GRUNT out the hard work of not days, not weeks, not years, but literally decades and life-times to find unknown facts and patterns which could not be discovered otherwise.  Its no glory job, that is for certain!

What we know from observations and research, over long time periods, produces some basic generalizations that I will break down into two categories.


1 ). Cold-Snowy Winter

For those wishing for a cold, snowy winter within the High Knob Landform, the southern Appalachians, and across the eastern United States in general, the following teleconnection phase combinations would be nice:

-AO
-NAO
+PNA
-EPO
+/-ENSO
+MJO
+A deep covering of snow across
eastern Canada and the NE U.S.A

 --NAO with --EPO = Prolonged Arctic Outbreak
[ Strongly negative NAO & EPO = Arctic Outbreak ].

The -NAO referring to the negative phase of the North Atlantic Oscillation, which possesses a rather high correlation with cold, snowy weather across the eastern United States.  A negative phase of the Arctic Oscillation also has correlation to more eastern U.S. troughing and coldness.

A look at the recent indices of these is illustrative, along with a peek at their short-term forecasted trend.

NOTE:  All the following graphics are courtesy of the Climate Prediction Center.

Observed Arctic Oscillation Index

An inspection of the observed AO index already shows a high correlation to recent weather conditions, with the -AO from July into early August being associated with unseasonably chilly summer conditions across the great Appalachians.

Note that the flip to a +AO, from mid-August through the month of September, also possesses a rather high correlation to the local change into humid, wet, and warmer conditions.

The return to a highly -AO during October was accompanied by a chilly month, with near to below average temperatures being widespread across the region.

The most recent index has mostly featured a +AO, and conditions in November have been mild compared to average.

Observed and Forecasted AO Index

With the above in mind, the forecasted trend is for the AO to go highly negative heading into late November and early December.  Could that mean a BIG pattern change to colder, snowy weather?

Let's look at the North Atlantic Oscillation, and see if it follows the AO trends.

Observed North Atlantic Oscillation Index

The observed NAO index pattern looks amazingly similar to the AO, and has also shown a high correlation to weather conditions observed within recent months.

The -NAO has been associated with cooler than average temperatures, and the +NAO intervals have been observed during periods which had near to above average temperatures.

The downward trend during November, toward the current -NAO, however, has not been associated with colder conditions.

Sometimes there is a small lag time ( otherwise, another forcing like +ENSO may be acting to cancel its effect ).

Lets now see what the forecasted trend is on the NAO.

Observed and Forecasted NAO Index

The NAO index is also forecasted to go negative during late November and early December.  So the score is 2-0 for a turn toward colder conditions ( 2 for / 0 against ).

[ NOTE: The AO and NAO are not predictable more than a few days to a couple weeks in advance, due to various reasons, and are not as good of a forecast indicator for longer ranges as they might appear to be ].

Let's keep marching onward to the Pacific North American ( PNA ) index.  A +PNA tends to be associated with eastern United States troughing, and western U.S. ridging, while a -PNA tends to help force a RIDGE in the eastern United States.

Observed Pacific North American Oscillation Index

As can be seen by the observed PNA index, there is also a good amount of correlation between cooler local conditions and +PNA formation, and warmer local conditions and -PNA development.

Lets see what the forecasted PNA is to do in coming weeks.

Observed and Forecasted PNA Index

The PNA is forecast to go positive during late November-early December, which again would support a change toward colder local conditions ( Score: 3 to ZIP ).

So there appears to be something upcoming.

A major pattern change toward eastern United States troughing, and colder conditions during the Thanksgiving Holiday to December 1 period.

Lets now look at the forecasted EPO index, since a strong +EPO tends to be associated with strong zonal flow across the Pacific, which is likely to spread mild, oceanic air into the United States. 

A -EPO is desired for colder air within the eastern United States and, as previously noted, when a --EPO ( strongly negative ) phase couples withstrongly negative phase of the NAO ( --NAO ), a prolonged arctic outbreak into the eastern United States is often likely during winter.

Forecast of EPO and WPO

Ensemble forecast model runs at NCEP ( the National Center for Environmental Prediction ), predict that the EPO will go strongly negative during the week of Thanksgiving.  So this is yet another factor favoring a major pattern change during the holiday period.

A unknown then becomes, what impact will the forcing from a moderate to borderline strong +ENSO have on these above teleconnections.

Remember, waves emitted from each will have to interact together, with the resultant outcome generating the type of weather conditions to be observed over any given area.

Ideally, a near neutral to weakly positive ENSO ( +/-ENSO ) is better for colder weather in the eastern United States.

The +MJO noted above, within the teleconnection list, refers to an active phase of the Madden-Julian Oscillation, with positioning that allows input of energy into the polar westerlies.  The MJO is an oscillation which travels through the tropics of the globe, with a 30 to 60 day frequency. 

The MJO influences the North Pacific jet stream, which in turn can help develop a PNA pattern.  If a +PNA develops, this makes downstream trough formation more likely across eastern North America, to again show how various wave supported oscillations can work together to impact conditions FAR away from where they actually develop.

Another important factor, that is itself relayed to the atmosphere and transfered in wave form, is mid to high latitude snow cover.

The covering of snow across high latitudes early in a season can be very important to the evolution and development of winter patterns.

Lets look at the current snow cover status across the Northern Hemisphere.

Northern Hemisphere Snow & Ice as of November 18

A 30-day loop of Northern Hemisphere snow cover changes:
http://www.natice.noaa.gov/ims/loop/nhem-1mo-loop.html

As the above well illustrates, REAL wintry conditions have been on the other side of the North Pole and across Alaska.  Rapid and huge increases in snow cover have occurred across Asia, deeply into China during the past month.

By contrast, the snow field has had a difficult time claiming and maintaining its hold on the southern half of Canada, and has been essentially absent from the lower Forty-Eight of the great USA, outside of the higher elevations of the Rockies, Cascades, and Sierras.

This does not initially bold well for a harsh winter in the eastern United States, but there is still time for rapid expansion and coverage of the white stuff into the Thanksgiving to Christmas holiday period.

The amount of snow cover across Asia can not be ignored, since a cross-polar flow could work to transport bitterly cold air masses into Canada, amid the long arctic nights, and eventually threaten the United States.

That would require our teleconnections to get into the right phases, such as a -NAO / -AO with a +PNA and -EPO.  If phasing were then to occur with a +ENSO enhanced sub-tropical jet stream, the stage could be set for some of the most severe winter conditions since the 1970s and 1980s.

[ From an ecological perspective, we NEED to have at least one SEVERE cold wave, with minimum temps dipping to -20 F below zero or lower, in order to kill out the Hemlock Wooly Adelgids ( Adelges tsugae ) which are threatening to drive our majestic, beloved, and so precious Canadian Hemlock ( Tsuga canadensis ) trees into extinction ].

How snow cover can alter the course of a winter will be highlighted in my Historical Climatology section below.

Despite the above favorable indices, toward a colder pattern by Thanksgiving, the generally favored and superior European Medium Range Forecast Model is not yet showing a definitive push of cold air, with establishment of a long-lived wintry period.

European 10-Day Forecast Charts - Nov 18

[ The RED lines on the panels above are the 500 mb geopotential heights, while the BLACK lines are the surface isobars.  A dip in the RED lines signifies a trough, while a bulge indicates a ridge, much like one observes when reading a topographical map.  A trough in the atmosphere is like a great valley, while a ridge is analogous to a great mountain ].

Here is the European Model Run for November 19 at 1200 UTC, for a comparison with the model run of 24-hours ago ( above ):

European 10-Day Forecast Charts - Nov 19

[ Note the differences between these two model runs ].

European 10-Day Forecast Charts - Nov 20

Note in the most recent model run above, from 1200 UTC November 20, that the longer range is becoming progressively colder, relative to the model runs of 24 to 48 hours ago.

It will be VERY interesting to follow the European model ( as well as others like the GFS, GEM, and UKMET ) through the next five to ten days, in order to see IF it begins to strongly reflect the wintry nature suggested by teleconnections highlighted above.

If it does not, then it could mean that the +ENSO may, indeed, be the BIG DOG and dominant WAVE-form to rule the 2009-10 winter season.  Time will surely tell.

Updated - TIME IS Telling

Time is indeed telling, as each new forecast model run of the European ( as well as others like the GFS, GEM, and UKMET ) are growing increasingly cold and wintry looking by the Thanksgiving Holiday.  Check out the latest run from this morning ( 1200 UTC on November 21 ).

European 10-Day Forecast Charts - Nov 21

The European is now showing the first widespread snow accumulation of the season, from the highlands of the southern Appalachians into New England, during the Thanksgiving-Black Friday period of this coming week ( especially along the western front range of the mountain chain ).

This is being echoed by the GFS and other models, with details of the event ( of course ) yet to be worked out.

Perhaps most significant, this looks to be part of a MAJOR pattern change that will present the region with a jet stream phased winter storm threat by the end of November.  Stay tuned!

[ An interesting point, made numerous times by forecaster Larry Cosgrove, of WeatherAmerica, is that the +ENSO enhanced sub-tropical jet stream is running much farther SOUTH than is found during more typical El Nino events of moderate nature.

Climatology agrees.  For example, instead of hammering southern California, the sub-tropical jet stream has been running south of the Golden State and passing across the Gulf of Mexico and up the Southeastern coastline.  This could be a VERY significant factor, with vast implications on the upcoming winter, should this trend continue ].

Update On The Update - November 28

The Thanksgiving-Black Friday event ended up being very weak, with generally 1" or less of snow across the High Knob Massif and higher elevations of the Mountain Empire.

Eagle Knob of High Knob - November 27
Image courtesy of Steve Blankenbecler

Just enough snow to cover the ground and high elevation roads, with a light coating of RIME on the trees.

COLD temperatures did allow some snow to linger across northern slopes of the massif into November 28, with early MINS in the 10s to lower 20s within colder basins and valleys.  BRRR!

The lack of local snow was thanks to a LACK of any Great Lake moisture, with very limited low-level moisture for the upsloping to work on ( despite ROARING winds which actually carried some of the snow across the windward side of the crest shown above, depositing less there ).

Some LAKE moisture allowed for 2"-5" snow accumulations to occur above 2500-3000 feet across the central-northern highlands of eastern West Virginia.

Despite the lack of snowfall so far during the 2009-10 season, the MAJOR pattern change noted above is still underway and will become apparent as December gets going.

All major indices are even more supportive than previously shown, with the latest -AO prediction being a classic example:

Observed and Forecasted AO Index

A strongly negative Arctic Oscillation is being forecast to occur into early December, to correlate with high latitude blocking and a southward suppression of the arctic-polar jet streams.

Get ready for some BIG changes!


2 ). Milder, Less-Snowy Winter

For those wishing for a mild, less snowy winter within the High Knob Landform, southern Appalachians, and across the eastern United States in general, the following teleconnection phase combos would be nice:

+AO
+NAO
-PNA
+EPO
++ENSO 
-A lack of snow cover across 
eastern Canada and the NE U.S.A

I will not go through each of these, as the impacts are just opposite to those noted above for their other phases.

However, I will note some interesting examples below in my Historical Climatology section.

I will also note that the ++ENSO refers to a strong epsiode ( strong El Nino ), such that warmth is more often than not dominant over coldness during the winter season relative to average.

That makes snowfall near to below average across the western front range and foothills of the Appalachians ( westward and northward of the HKL and Tennessee Valley Divide ).

In such a case, the train of waves rippling outward from a STRONG El Nino acts to overwhelm the other waves over any given area ( at least, in the seasonal MEAN ). 


The Bottom Line......

So what is the Good News?

It is that we have identified many major atmospheric teleconnections which impact global and regional weather conditions.  These can give us a guide to go by, but most are not as consistent and predictable in advance as are ENSO espisodes ( i.e., El Nino and La Nina )!

Once running, however, some have long-time scales ( like the PDO and QBO ) and can help generate a known setting within which ALL the vast array of other wave disturbances play.

Through long-term, daily weather observations and research a climatology has evolved to help guide us into the uncharted future.

I will highlight this more below.

So what is the Bad News?

The bad news is that the future is UNCHARTED ( with very few exceptions ) beyond the short-term.

I really do not want to focus alot on the bad news, since I always try to keep a positive outlook.  But the BAD news is that the state of our science, as I've noted before, is simply NOT GOOD ENOUGH to detail weather conditions for any given location more than a few days to a week in advance. 

Although 7 to 10 day forecasts look nice on TV, most are simply for appearance, as DAY 7 from DAY 1 will almost always be much different, sometimes radically so, from that which was initially predicted on DAY 1.

Thus, anything beyond a week is into the realm of pure fantasy, and guess work, when it comes down to giving any significant details ( predictability actually begins getting PUSHED HARD at 3 to 5 days ).

Its not a forecaster's fault, unless the forecaster blatantly tries to act like they always know what is going to happen a week from now ( i.e., just for the SHOW of acting or lack of knowledge ).

It is the combination of all the waves rippling through the atmosphere, as I've highlighted previously, from ALL the many known plus UNKNOWN disturbances, that takes initial forecast model input and drives it into pure CHAOS ( and that assuming the initial input data is GOOD ).

In fact, that is the definition of chaos, as the initial input increasingly departs from reality over time and creates a highly UNSTABLE solution which is not predictable from the starting point ( i.e., the final solution ends up being radically different from actual, real conditions ).

[ In reality, the initial INPUT data into forecast models is FAR too limited in both space and time to even begin to fully handle the complete state of the atmosphere.  Thus, forecast models often struggle with just predicting conditions during the upcoming 24 to 48 hours ].

That MUST be understood by everyone, since too much is often expected of forecasters ( despite all the fancy looking graphics of today ).

On the other hand, forecasters must not assume too much and be willing to take responsibility for relaying to the general public that the state of our science is simply NOT yet good enough to KNOW exactly when and where a tornado will strike, for example, or what conditions will be like where you live far into the future.

It's like a young couple planning a wedding asking:
What will the weather be like at 3 PM in the afternoon a month from this Sunday? 

The HONEST answer, it is NOT POSSIBLE to know. 

Period!

Historical Climatology

Tussock Moth Caterpillar ( Lophocampa caryae ) - High Knob
Photograph by Roddy Addington - © All Rights Reserved.

The Tussock Moth Caterpillar above was captured by Roddy on High Knob during a day in which he said, "it looked cold, and out of place."

Weather conditions can also be out of place for the season during periods with many competing forces, fighting to control the great atmospheric domain.

The current global warming cycle on Earth, which is very REAL, in combination with a large-scale forcing factor like the +ENSO teleconnection, weights models used by the Climate Prediction Center too much, in my own personal opinion, and skews their needed objectivity away from the best possible solutions.

Here are the official forecast maps from the Climate Prediciton Center for the upcoming winter season:

[ These initial forecast maps were made on October 15, 2009 ]

December-February Temperature Trend
Courtesy of the Climate Prediction Center

The CPC official trend on these graphics calls for below average temperatures and precipitation across the local mountains. 

December-February Precipitation Trend
Courtesy of the Climate Prediction Center


[ UPDATED forecasts made on November 19, 2009 ]

December-February Temperature Trend

An inspection of the new CPC map trends, reveals very little change since their mid-October forecast.

December-February Precipitation Trend

Here is a link to an extensive, detailed report on the current evolution, status, and prediction of ENSO ( El Nino ) that is updated with passing time:


Many forecasters like to use "analog" years, with similar upper air or surface conditions as observed during the present year ( leading up to a winter season ).

Historical climatology shows that they can, indeed, be helpful, but it also reveals that EVERY new season is different, with outcomes that end up being unique in space and time.

A look back at +ENSO episodes reveals the above, with each event being different, due no doubt to modulation by complex wave interactions via the myriad of atmospheric teleconnections and other factors which are running at the same time as El Nino ( with many positive and negative feedbacks among them ).

External forcing factors, not yet even mentioned, must also be considered, such as the currently long SOLAR Minimum ( lack of sunspots ) that generated the least sunspot activity in a hundred years during 2008 ( with a similar pace being observed during 2009 ).

In the MEAN, as climatology will eventually GRUNT out, the tendency during +ENSO periods has been for below average precipitation & above average temps across western slopes of the Appalachians during the time of maximum ENSO influence ( generally the December-February period of meteorological winter ).

Local orographics skew this, with the wettest, coldest, and snowiest conditions being across the High Knob Massif, and along the crestlines of the northwestern-southeastern flanks of the HKL into windward slopes of the Tennessee Valley Divide ( which includes the Cumberland Mountain arm of the HKL and the lofty terrain of its great Cumberland Gap National Historical Park ).

Although that could be said of any given cold season, the distribution of the precipitation within the lifting zone of the High Knob Massif, in particular, is skewed from the more typical SW-W-NW flow dominated regime toward its S-SE-E facing crests, basins, and slopes.

The favored zones being shifted due to more S-SE-E flow events and forced upsloping along those slopes of the sprawling massif.  This also includes southern-southeastern slopes of the adjacent Black Mountains, along the VA-KY border.

Total precipitation amounts ( rain + melted snow ) for the winter season generally end up being ABOVE average within these favored orographic corridors.

Above average winter precipitation is also favored during +ENSO episodes along the Blue Ridge, with spill over into the Great Valley during strong El Nino events.

By contrast, below average cold season precipitation amounts are more likely to dominate northern Wise County, and the central-northern portions of Dickenson and Buchanan counties, due to increased downsloping on S-SE-E air flow trajectories.

This sub-average precipitation regime of +ENSO episodes tends to increase toward the west and north of the Cumberland Mountains, into the foothills and bluegrass of Kentucky and West Virginia, as well as into the lowlands of the Ohio River Valley. 

The 1982-83 ENSO, which has been the strongest positive phase on record, was interesting in that it resulted in winter snowfall totals which were 100-150% of average from the High Knob Massif across the Great Valley of northeastern Tennessee-southwestern Virginia.

This trend continued eastward across the Blue Ridge into the Piedmont, with seasonal snowfall totals which ended up being 200% of average around the Nation's Capitol.

Snowfall totals within the Clintwood to Wise corridor were 90-100% of average during the 1982-83 season, with a decrease to only 50-90% of average being observed across most of Kentucky and West Virginia.


A Mega-Snowstorm
Risk With +ENSO?

From a long-term climate perspective, it should also be noted that 3 of the 4 largest snowfalls of the past 60 years across the western front range of the Cumberland Mountains occurred during a +ENSO phase of the oscillation ( El Nino ); although, only 1 of those occurred with a strong El Nino within the critical 3.4 sector of the equatorial Pacific Ocean.

Thus, a +ENSO phase is somewhat suggestive of an increased mega-snowstorm risk, despite the general El Nino trend of near to below average seasonal snowfall to the west and north of the HKL and Tennessee Valley Divide.

[ The great snowstorm of November 1950 occurred during a negative ENSO ( La Nina ) phase ].


Harsh Winter's Occurred 
During Weak +ENSO Phases

The year of 1976 has been batted around as an analog year to the present event, however, it was much different.  Only marginal ENSO conditions occurred during the 1976-77 season, with above average sea surface temperatures being generally restricted to the El Nino 1-2 regions near the South American coast.

The 1977-78 season, however, did display a more typical and expansive region of positive sea surface temperature anomalies into the central equatorial Pacific Ocean.

These late 1970's winter seasons are, of course, legendary for their harsh winter conditions, with brutal cold and mean snow depths reaching 42"-48"+ across upper elevations of the High Knob Massif ( during just the seasonal buildup of the snowpack ).


The Importance of 
Higher Latitude Snow Cover

The importance of placement of high latitude snow cover was taught during the back to back winter seasons of 1995-96 and 1996-97.  These two winters generated the largest snowfall differences ever documented locally.

The 1995-96 winter established new seasonal snowfall records for Virginia, with 124.2" in the town of Wise and more than 200" at the summit level of the High Knob Massif.

The 1996-97 season was, by dramtatic contrast, a grand snow BUST with 100.2" LESS snow in Wise ( only 24.0" fell during the entire winter ).

The NAO was in its negative phase during both winters, with a prolonged -NAO showing up for the first time since the middle 1980s ( complete with abundant high latitude blocking ).

The SOI classification scheme places the 1995-96 and 1996-97 winters into the neutral ENSO bracket ( so that ENSO was considered to basically be a non-player during both seasons ).

The big player, as it turned out, was development and distribution of snow cover across Canada.

During the great 1995-96 season, an unusually deep field of snow developed across southeastern Canada and the northeastern United States by late autumn of 1995.  This set the stage for record breaking snowfall across the western slopes of the Appalachians, as the polar vortex became established over SE Canada.

The persistent location of the polar vortex kept the baroclinic zone ( the zone of max thermal contrast ) in a position to feed energy and moisture into one developing wave disturbance after another, with cold air in place to support abundant and heavy snows ( especially along the W-NW-N slopes of the mountains ).

During the next winter, by contrast, early season snow cover formed across western and south-central Canada, with expansion southward into the Rockies and Plains by late autumn.

The temperature contrast between the snow field and bare ground to the south, set up the baroclinic zone in a manner that held the storm track northwest of the Appalachians.  This kept the region within the rainy, warm sector of approaching wave disturbances, and dry slotted the area in their wake ( with often no snow at all despite influxs of cold air ).


LINKS to Winter 2009-10 Forecasts

Note: The inclusion or exclusion of anyone in the list below is not an endorsement, nor a rebuke, of their work, but merely offers different perspectives from different places across the nation.

Western North Carolina 2009-10 Winter Forecast:
http://www.booneweather.com/Fearless+Forecast

Washington, D.C., Area 2009-10 Winter Forecast:
http://voices.washingtonpost.com/capitalweathergang/2009/11/capital_weather_gang_2009-10_w.html

Weather Advance 2009-10 Forecast for USA:
http://www.weatheradvance.com/winter-2009-2010-forecast

NWS Forecast Office - La Crosse, Wisconsin:
http://www.crh.noaa.gov/arx/?n=winter200910outlook

Dean Grubbs - Raleigh, NC., Climate Examiner:
http://www.examiner.com/x-17371-Raleigh-Climate-Examiner~y2009m11d24-Winter-200910-Old-man-winter-returns--part-2

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