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.
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.
|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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