1ST  ISSUED   NOV 12  privately...

 


Text  that is  in  RED   BOLD  has been   so designated   because   it contains   KEY ideas.

 Throughout this  forecast      you will see   the  acronym    "CF" used.   The two   letters   "CF"     stands  for    "Consensus Forecast"    which is  term that I use   to describe  the general view or a summary of what most  PWSIP  (private weather  service  Information Services)      and / or   the   CPC Winter  2008-09 forecast.  The CF is very important in determining how the seasonal trade in Energy and Agriculture markets will unfold and has some  tangential  aspects  to the weeks 2 forecast and   30 days  as well.     For example… State DOTs will often significantly lower their Salt and Sand purchases if the CF is for a Mild winter in their areas.    The CF often consists of  

a) the CPC (Climate Prediction Center) …whose forecast carry a lot of weight...  
b) large well known Private Weather Service Information Provider (PWSIPs) and      
c) some well known Energy/ Ag forecasters.

 

 

 

THE  BOTTOM  LINE 

******* There will be  a  MID WINTER    UPDATE      JAN 15*****

The winter of 2008--09 as a whole will average out to be very close to normal for much of the country except for the Southwest and Great Basin regions. There will be intervals of intense cold... prolonged intervals of below normal temperatures... as well as intervals of Above Normal temperatures and a couple of weeks of serious warmth.

 DEC 2008 relative to normal will probably be the coldest of the three winter months as well as being the coldest in  actual overall temperatures. The cold pattern breakdowns in January and the potential exists for at least a couple of weeks of milder than normal temperatures. By the time we reach February 1 or so... much of the central and eastern CONUS could be fairly close to normal with respect to temperatures for the Winter.   With regard to February WxRisk.com does not agree with the consensus forecast which seems to be for a milder than normal month east of the Rockies. Instead I see Below Normal temperatures over the  eastern  the Midwest and Great Lakes and Interior  East Coast and New England... a fairly small band of Near-Normal temperatures across the western  Plains  and the  Rockies.. and an  area of Above Normal temperatures over the southern third of the nation from western Texas to the Carolinas and Florida.

 

We are now in the nebulous period of seasonal or long-range forecasting which is not quite a full science and not guesswork and not intuition... not exactly an Art. The advances and understanding of the atmosphere over the past 10 to 20 years has been really quite amazing and it has definitely paid off with more rational and reasonable seasonal forecasts.

With any sort of seasonal forecast... the forecaster has to make several critical assumptions about some important aspects to the atmosphere. It is these critical assumptions that  forms   the  premise  of any  seasonal forecasts. While this may seem obvious to some... by  recognizing this   Paradigm  one  can  recognize the inherent risk in a Seasonal forecast. If for example I assume that we are going to see a strong El Niņo event during the Summer months of the particular year... but that event does not develop or is much weaker than forecasted... there would be very little chance of my seasonal forecast verifying.

 

CRITICAL  ASSUMPTIONS 

 

In the Winter of 2008-09  these Critical features will be:

ENSO: for those of you who are not particularly savvy with regard to these different climatological  and Ocean/ atmospheric features the term "ENSO" refers to the three different types of Sea Surface Temperature Anomalies (SSTA) which exists along the equatorial Pacific from the Date line to the coast of Peru.:  El Nino ( warm SSTAs)  La Nina (cold SSTAs)  and La Nada   (Neutral  SSTAs).   Unlike the last several years the Winter 2008 -- 09 will NOT see  ANY  sort of ENSO  event.   The   Winter of 2007-08  featured a  Moderate to strong La Nina... and the  Winter of 2006-07   featured a  Moderate to  Strong El Nino  event.   This Winter however conditions along the ENSO regions will be very close to normal for most of the Winter with a slight bias to the cold side.   It is still   POSSIBLE  (but not likely)  that during the Winter the ENSO regions could cool enough to just barely qualify as a weak La Nina event.    Outside of that event however the key point here is that  with   Neutral  Enso Conditions  (called  "La Nada")    we do not have a overpowering influence  driving the atmosphere across the Pacific and into North America ...which  essentially is what moderate / strong El Nino and La Nina events do. This means that  other factors are going to be much more in play and have a much bigger impact than what we have seen over the few Winters.

 

QBO: The QBO for most of the Summer and Autumn has been strongly "positive".... or blowing from the West  to East  but  data  shows it has started to weaken slowly.   Strongly positive QBO values can have a significant impact on the overall patterns during the Winter months especially when you have neither a El Nino or La Nina. Generally a Westerly or Positive QBO will aid the Pacific Jet...  which  means  that the build up of Cold air over Western Canada is constantly  under  "attack"  by Milder Pacific  air. In addition   +QBO or   Westerly QBO generally inhibit a stormy pattern for the Eastern third of the CONUS and  favor a  Positive  NAO  (North Atlantic  Oscillation) and  AO  (Arctic  Oscillation).  Research shows that as the QBO begins to weaken and drop in value towards zero... the pattern becomes distinctly more favorable for blocking patterns to develop over the high latitudes of North America and Greenland.

The QBO is going be very important come the second half the Winter. If the value does drop towards zero by February... then there is some tendency to see a stormy the normal pattern east of the Mississippi River.  On the other hand if the  +QBO does NOT  drop  (which would be  very Unexpected)   towards  Neutral the   2nd  half of the Winter  could   be   mild  east of the   Rockies.

 

PDO -- The PDO or "Pacific Decadal Oscillation" a long-lived climate pattern that exists over the northern Pacific Ocean .
The PDO Phase involves the location and intensity of large pools of warm and /or cold Seas Surface Temperature Anomalies (SSTAs) in the central and eastern areas of the Northern Pacific and these large sea surface temperature anomalies in the ocean can and do impact the climate over North America in a profound way.

When the PDO is  in a negative  cycle  ...which can last  for   many years...  the  PDO  tends to run  Negative phase far more than Positive  phase on a Monthly Basis.   And   when the PDO is  in the   Positive  cycle  it  tends  to run Positive    phase far more often  than Negative.

Because there is not going to be a sustained or significant El Nino or La Nina this Winter the impact of the PDO is going to be stronger than normal.

For most of the Summer and Autumn the PDO has been in Strongly negative phase. Many of the consensus forecast have assumed that the strong negative phase of the PDO is going to continue right through Winter. Wxrisk does NOT agree. I  see the PDO   weakening  slowly but  steadily   during the   course of the  Winter  with   JAN / FEB   featuring  weak  -PDO  Phase.

 

NAO-- The NAO or North Atlantic Oscillation is one of the major configurations in the Jet stream patterns over the Northern Hemisphere atmosphere. The NAO configuration covers a geographical regions from eastern or northeastern Canada to Greenland and over towards Iceland / Ireland and it is particularly important in Winter months when it exerts a strong control on the  weather  pattern over the Northern Hemisphere.   There are several manifestations of the NAO but the feature is extremely hard to predict. When the   NAO is  in the Negative Phase the   Polar Jet is forced south  into the  CONUS  resulting in colder  and stormier patterns.  When the   NAO is in the  Positive   Phase  the core  of the  coldest air  has trouble coming  south and  the threat of  serious large scale   cold air outbreaks over   central and eastern   CONUS is  reduced.     There are no Known methods for doing so but over the last several years there are have been some "preliminary"  findings that some some promise in this matter.   Again I have to  point out   that   over the last  few years  we have NOT seen  sustained intervals   of  -NAO  activity  because  of the over powering   effects   that strong La Nina (winter  2007-08)   and  strong El Nino  (winter 2006-07).   This Winter   I  am assuming   there will be NO  Moderate or strong ENSO   events which   simply as a matte of  default allow  for  at least   SOME  intervals  of  sustained  -NAO  intervals.   This will NOT only lead to a colder  overall pattern for at least Part of the Winter    over the central and eastern CONUS but also  a   snowier one for   the  eastern  Conus.

 

SOIL MOISTURE- unlike the last two winters which  featured significant dry areas over the Deep South this time around the Soil moisture maps clearly show two areas of significantly wetter than normal soil moisture. One area is located over the Plains which has had a very wet Autumn and the other region is across the Great Lakes and New England which is also seen an active & stormy Autumn.

WxRisk.com believes that in seasons where there is not a overpowering or significant El Niņo or La Niņa signal the soil moisture can be a important consideration and significant clue to how the mean pattern is going to develop. This aspect of the forecast is often overlooked by many less experienced climatologists and meteorologists.

The current maps from the CPC  and the Drought Monitor webpage shows that the large area of long-term dryness over the Rockies and West Coast as well as the Tennessee Valley continues to weaken but  are increasing over the  SW states.   For most of the Autumn of 2008 we have see Above Normal rainfall and wetter  than Normal soil conditions over the Plains and to a lesser extent across the Great Lakes into northern New England. WxRisk sees this as an Important clue in figuring out the puzzle of the mean region trough position during the Winter months.

 

SEASONAL TREND: seasonal trends matter. Recent research over the past few years in such distinguished periodicals as the Journal of Climate have shown that October and November patterns sometimes give a pretty good clue as to where the overall pattern  will   develop for the Winter.  Again this tends to be far more important when there are neutral ENSO conditions like we will have this Winter (and  conversely OCT & NOV seasonal trends tend to have a lot less impact when there are Moderate La Nina / El Nino events underway).

There is a tendency these days to issue Winter forecasts really early sometimes as soon as mid-September. This of course is driven by the demands of the energy and have a cultural markets as well as public concerns. However making a winter forecasts this early in time increases the impact of the critical assumptions problem that all seasonal forecast of how to deal with.

For example there was widespread consensus forecasts that the winter of 2005 -- 06 was going to be severely cold winter for much of the central and eastern US. Many private and well-known energy forecast companies was pushing this idea heavily. That forecast was based upon several critical assumptions... one of them being the belief that the 2005 record hurricane season had some sort of impact upon the Winter and that we would see a weak La Nina which tends to support a stormy the normal pattern for the eastern half of the Conus. The weak La Nina event never developed and the fallacious connection between  severe  hurricane season of 2005 and other very active hurricane seasons of the past 100 years... was exposed for the nonsense that it was.

The seasonal trend of OCT and NOV 2008 has features several significant systems along the East Coast and several significant systems over the Plains and Great Lakes. I believe this is a precursor of the overall pattern we will see for large portions of this Winter.

SNOW COVER over the NORTHERN HEMISPHERE: again this is one of these aspects to seasonal winter forecasting that often gets overlooked. Early-season buildup of snow and ice in October and November across the northern hemisphere and the ice Shield buildup across the Arctic region can be significant  factor   IF  there is  no   dominating  Moderate  / Strong ENSO   event during the winter months.

As you may have heard the snow and ice cover over the Arctic regions this past Summer reach its lowest  point recorded history. Which is not saying all at much.. given how long we have been able to measure such things. However over the Autumn the ice   has  made a amazing comeback and the snow cover which start off far below Normal has now approached normal levels and may have even surpassed it over the past week.

Snow cover itself is not a significant factor most of the time with regard to figuring out a winter seasonal forecast. However it can have an impact on the intensity of and size of a cold   air masses as  they travel south into the CONUS  or on those rare  occasions  where  cross  Polar   Jet stream flow  from Siberia  is established.   A large snow cover over the Arctic regions in Canada does not necessarily mean that the winter over the CONUS will be cold and snowy. There are  numerous cases where the snow cover has been Much Above Normal and we seen a mild winter in the  CONUS . But on the other hand there are very few cases where there has been Much Below Normal snowfall cover across Canada and the Arctic region and the Winter  over the  CONUS   was a  cold one.

 

 

FORECAST MAPS

DEC  2008  JET STREAM DEC  2008  PRECIP DEC  2008  TEMPS
JAN 2009  JET STREAM JAN 2009    PRECIP JAN  2009  TEMPS
FEB 2009  JET STREAM FEB 2009 PRECIP FEB 2009  TEMPS

 

 

 

KEY ASPECTS OF THE COMING WINTER

 


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