1ST ISSUED NOV 12 privately...
|1. REVIEW OF SUMMER 2007 FORECAST||8. ENSO FORECAST FROM CLIMATE MODELS|
|2. BOTTOM LINE||9. MEI|
|3. KEY ASPECTS TO WINTER 2007-08||10 HURRICANE SEASON 2007|
|4. FORECAST MAPS||11 NAO|
|5. HOW WAS THIS FORECAST PREPARED||12 PDO|
|6. AUTUMN 2007 PATTERN||13 QBO|
|7 EL NINO STATUS 2007-08||14 SNOW COVER|
This forecast has been delayed a bit because of the impending move from my current location to Near Leesburg VA at the end of NOV 2006. Clients get it first... then the web site and the general public but with the move well something was going to delayed. Pull up a Hot cup of Tea and some cake.
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 NWS forecasters are saying. The CF is very important in determining how the seasonal trade in Energy and Agriculture markets will unfold as well the operational side of the weather biz. 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.
REVIEW of SUMMER 2007
After careful consideration I have come to the conclusion that the WxRisk Summer forecast of 20076 was OK but not my best.... the Summer 2006 Seasonal Forecast was far better. My JUNE 2007 was Not good as I missed the rainy pattern and cool temps over the central and Lower Plains and I was too cold over the Midwest and Northeast but I did get the heat over the western CONUS. JULY 2007 also less than a good forecast as well.. again I was too cold over the Midwest and Northeast and way too dry over the Lower Plains but I did get the extreme heat over the Western CONUS. AUGUST 2007 was my best month as I got the heat over the Deep South and Lower Midwest almost perfectly.
The Hurricane forecast for 2007 was again Fabulous.... as good as my 2006 Hurricane forecast ( where I went for only 12 named TCs). for 2007 I said this
This time around WxRisk.com does see an INCREASED probability of significantly More active Hurricane season for 2007. However where I disagree with the Consensus Forecasts is the matter of which regions of the US Coasts are more likely to be hit.... ( Gulf / Florida / SE US coast / NE US CONUS). I see a much reduced chance of the central and northern portions of the Texas coast being hit this year....as well as the central and eastern Gulf as well as the SE Coast. But There is an increased chance of areas from Brownsville /southern TX southward into northern Mexico getting hit ... Nor do I see the 2007 Hurricane as a New England year either...
click in IMAGE to see map
ok BUT NOT MY BEST---
sUMMER arguably the best seasonal forecast I had
ever issued on this web site over the past six or seven years. And quite
frankly from what I've seen from every else's forecasts... it appears that my
Summer 2006 forecast was best one out there. Period.
Without going into a lot a detail because I simply don't wish to... suffice to say my Summer forecast has generated quite a bit of reaction and business from the various Energy and Ag markets.. trading houses and traders ... which makes me happy.
In my Summer 2006 forecast ...which again you can see at this LINK... I argued that the
weak La Nino was collapsing in May and therefore we would not see a drought over the WCB
that the drought would be confined to the Plains and eastern Rockies regions
that the collapse of the La Nina would have significant impact on the 2006 hurricane season
The vastly different phase of the QBO from 2005 meant that we are going to have a significantly different hurricane season for 2006
that overall Hurricane activity would be much lower than what the consensus forecast was calling for
the overall pattern did
not support significant hurricane activity along the East Coast but rather
several near misses.
|ACTUAL JUNE TEMPS||ACTUAL JULY TEMPS||ACTUAL AUG TEMPS|
|ACTUAL JUNE PRECIP||ACTUAL JULY PRECIP||ACTUAL AUG PRECIP|
THE BOTTOM LINE
******* There will be a MID WINTER UPDATE JAN 15*****The Winter of 2007-2008 is going to be a mild Winter for most of the CONUS but it will be an active Winter as well. The West Coast (especially the Pacific Northwest) as well as most Rockies and Upper Plains will see the most active of the Winter weather and has the best chance of seeing temperatures Below Normal. For most of the Winter the Central Plains -- OK to NEB -- as well as Midwest is going to be the "battleground" while the Deep South will feature dry conditions and abnormally warm temperatures. In the Northeast US.... New England should see temperatures somewhat Above Normal in the General sense but there will be significant cold intervals as well. However the Middle Atlantic states including the big cities of the I-95 corridor from New York down to Richmond will see several bouts of Above and Much Above Normal temperatures.
The pattern will bear a striking resemblance to the Winter of 2005 -- 2006 and the Winter of 1970-71. In many ways this Winter will be a compromise between the two since I do not see the Winter 2007 -- 2008 as being as warm as the 05-06 Winter and not as cold or a snowy as the 70-71 Winter .
For those that have read my seasonal forecasts before you know that there have been times when I have gone against the CF or consensus forecast ( Hurricane season 2006 Winter 2005-06 just to name a few) ... I have done so with good reason and for the most part those contrarian Winter and Summer forecasts worked out quite well. However in this particular instance -- the Winter 20007-08 forecast -- I think the CF (consensus forecast) is going to be correct. That being said there are some surprises and issues which have to be dealt with. As a general rule there have some improvements over the last 10 years with regard to seasonal forecasting. But one the major sticking points I have with seasonal forecasts whether they are government or private forecasts is that there is too much focus on question of which areas will see Above Normal or Below Normal Temps or the precipitation question and not emphasis on the underlying features. WxRisk seasonal forecasts are premised on the idea that by focusing on more underlying large scale weather features a more complete picture or "paradigm" develops. That is to say a more complete scenario of how of the upcoming forecast is formed. The advantage in doing a season forecast in this manner is that it enables a forecaster to stay on top of any changes or surprises that might be developing as the season begins to reveal itself.
In the general sense the overall Winter pattern for 2007 -- 08 is going to feature the mean trough position being located either over the far eastern Pacific /West Coast or the western third of North America and a mean Ridge position over the Southeast US. The combination of these stronger than normal Pacific Jet stream... the typical climatalogical pattern one sees with a Moderate La Nina.... the pool of anomalously cold sea surface temperatures over the eastern Pacific (negative phase of the PDO) and the effect of the extremely strong easterly phase QBO (reminiscent of what we saw in the autumn of 2005) will all contribute to ensure that the mean proposition is going to be located over the western portions of North America/ West Coast of the CONUS.
Since the basic laws of physics and meteorology say that for every Ridge position there must also be a trough.... the placement of the mean trough position over the West Coast means that "downstream" there must be a corresponding Ridge. That Ridge CAN be located somewhere between the Plains and Bermuda.
What determines WHERE this downstream Ridge position " sets up" can be several factors. However going into the Winter of 2007-8 we have an important and unusual feature which does not typically exists going into the Winter months. I am referring to the large and intense area of the drought over the Southeast CONUS.
It is the position of WxRisk forecast that the Winter of 2007 -- 08 that the interaction between above mentioned seasonal factors ( Moderate La Nina Very strong -QBO -PDO and the late Autumn pattern) along with the large drought area over the Southeast will ensure that the downstream Ridge position.... which could be located anywhere from the Lower Plains east towards Bermuda... is going to "Lock in" the mean Ridge position over the Southeast for much of this Winter.
There will of course be times when the Mean southeast US Ridge is almost nonexistent or playing a minimal role in the overall pattern. But on a large scale or seasonal perspective the ridge will be an important feature for this Winter.
|DEC 2007 JET STREAM||DEC 2007 PRECIP||DEC 2007 TEMPS|
|JAN 2008 JET STREAM||JAN 2008 PRECIP||JAN 2008 TEMPS|
|FEB 2008 JET STREAM||FEB 2008 PRECIP||FEB 2008 TEMPS|
Finally in the WHAT CAN WRONG ? department my focus is on during the middle and second-half of the Winter. It is possible that the moderate La Nina may continue right through the heart of Winter and not begin to break down until late March or April. If that is the case there is not going to be any significant change to the overall pattern in mid-or late February.
Another concern has to be the weakening of the strong easterly phase of the QBO which may occur late in the Winter and Spring 2008. The question is whether or not the weakening of the QBO will occur in time to affect the last third or 25% of the Winter season.
And lastly the October monthly reading of the NAO was positive. There is some indication that suggests a correlation between the October NAO phase and the inverse or opposite phase during the Winter months. If during the Winter months there is a sustained negative phase of the NAO over Canada and Greenland... there could be major shift in the overall pattern with the Northeast US turning quite stormy and cold.
KEY ASPECTS OF THE COMING WINTER
There are several critical assumptions which ALL extended and long-range and seasonal forecasts are based upon. By emphasizing these features it becomes possible to develop that large-scale view of how I see the season unfolding and what to expect with trends. In the Winter of 2007-87 these Critical features will be:
LA NINA...Currently the Moderate La Nina that has developed in AUG had held steady at Moderate levels from Early OCT thru Mid Nov 2007. The Moderate La Nina will hold its intensity through Mid Jan...possibly later. There is also the issue of when and How the La Nina decays from Moderate to Weak intensity which could have significant impact late in the Winter and early in the Spring of 2008.
QBO --the QBO is currently in the extreme Negative Phase (blowing from West to East). Its two most recent readings (Sept and Oct 2008) is the 2nd most intense East QBO values ever recorded and and are a very close match to the Most intense East QBO phase of all time ( Sept / Oct / Nov 2005). Moderately strong East QBO events strongly support Blocking patterns over the North America but severely negative QBO values strongly support progressive weather patterns... restrict large scale Arctic outbreaks and often play Havoc with Model performance in the week 2 time frame . More details on this will be provides in the full report
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. Currently the PDO is in a negative phase or Mode as there is a large areas of Colder than Normal SSTAs in the Eastern Pacific. This strongly supports the Mean trough Position in the Jet Stream over the eastern Pacific/ West coast.
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 climate of the Northern Hemisphere. There
are several manifestations of the NAO but the feature is
extremely hard to predict. 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. Last Winter the NAO turned
strongly Negative in Mid January and Locked into place
which set up a dramatically different
second half of the Winter 2006-07
(Jan 15- March 15)
SE DROUGHT -This is an unusual feature for the Winter 2007-08. The severe and large drought that developed over the Deep South in the Summer of 2007 has continued thru the Autumn. The features mentioned above (-PDO Moderate La Nina -QBO etc) tend to support the Mean trough position in the Jet stream over the West coast/ Far eastern Pacific at least through the 1st half of the Winter. This in turns means that downstream of the trough thee is going to be a Ridge which might be located anywhere between the Lower Plains and Bermuda. However with the large drought over the SE CONUS will focus the Ridge locking into Place over the SE.
SEASONAL TREND --So far the seasonal trend has supported a progressive pattern over the northern hemisphere and especially North America. There has been very little high latitude blocking and very little sustained -NAO over Greenland and / or northeast Canada. Most of the storm track activity over the past 60 days has been over the Plains... upper Mississippi Valley... and Great Lakes. There have been a few significant events for the East Coast but only one classic Nor'easter. The medium and extended range forecasts from the various global climate models in the week 2 timeframe had been unbelievably bad... which is to be expected given all the above-mentioned parameters.
The month of November 2007 so far has turned out to be fairly cold over the eastern half of the CONUS which has led some to speculate that we might be headed for a colder pattern in the Consensus Forecast is indicating. However the data clearly shows that November's that featured moderate La Niña tended to feature a colder than normal November.
HOW THIS FORECAST WAS PREPARED
We have entered a new stage and weather forecasting over the last several years. While academically the interest has been in mesoscale features... the business concern as the climate continues to appear to become more unstable has been in 30-day and seasonal forecasting. There are several different techniques that meteorologists use in making a seasonal forecasts.
Among these various methods is the use all for "ANALOGS"... the SSTA-- sea surface temperature anomalies in the Pacific and Atlantic oceans... and seasonal indices and patterns (such as the PDO in the QBO and NAO features) new climate forecasting models.
THE USE OF ANALOGS
Many (but not all) forecasters use "Analogs" to help make a seasonal or monthly forecast. In weather forecasting the use of analog is an attempt to understand the seasonal forecast period based (in past) upon similarities between a particular set of parameters. The idea is by searching for similarities with other years or seasons it gives a forecaster some clues as to how the monthly or seasonal forecast may develop. .
For example one may consider the fact that most US winters during strong El Nino years bring warm and dry conditions to the Upper Plains and Midwest and rather wet and cool conditions to the Deep South and changeable conditions in the Northeast. Or a forecaster may look at say the past 6 months... 12 months... or 18 months worth of temperature and precipitation data over a certain section of the country and use those similarities to the current situation to assist them in making the monthly or seasonal forecast.
Done the correct way the Analog method has validity to it. But the key thing to keep in mind is that when you are choosing a analog year you must choose one which matches the current set of conditions. For example to simply assumed that all El Nino events produce ONLY one set of conditions in the winter months is of course folly. Some of the most severe winters in the last 100 years have been El Nino winters and likewise.... some of the most Mild winters in the last 100 years have also been El Nino winters.
On the other hand some forecasters hold the view that analogs are not very helpful since weather records are incomplete or not sufficient enough to be considered as complete data source. For most locations temperature and precipitation data only extends back 100 or 130 years and accurate Upper Air maps only go back 70 years at best . That argument is Valid. Thus ANY seasonal forecast using analogs that is based on ONE parameter is a very risky and has a high degrees of failure built within the forecast.
One way of getting around this is to use several factors parameters and cross matching the analogs to look for common ground.
AUTUMN PATTERN 2007 SO FAR...
While in important not to read too much into the autumn pattern it can be helpful in determining whether or not some of the expected conditions are in fact developing. As I have already stated I anticipate a Moderate La Nina event to last most of the Winter as well as a moderately strong negative phase of the PDO and a very strong easterly or negative QBO. What I have attempted to do in the autumn of 2007 is look to see if there are any clues in the autumn pattern which support the forecast hypothesis I have developed for the winter.
September and much of October featured abnormally warm conditions for much of the central and eastern CONUS. In late October and for most of November the pattern switched with most of eastern US seeing temperatures turning colder than normal for this area. However the turn towards a colder than normal LATE November over the eastern third of the Conus is not unusual for moderate and strong Nina events and there is bias to support Cold nor is it uncommon for November is that feature -PDO events either.
However WxRisk sees something far more important than the temperature pattern shift that has occurred in the 2nd half of DEC over the central and eastern CONUS. That would be the clear and obvious rise of the enhance or stronger than Normal Pacific Jet. As stated above in the CRITICAL ASSUMPTIONS section WxRisk sees the Much enhanced Pacific Jet as a serious factor over all of North America for the Winter of 20007-08.
THE LA NINA / STATUS FOR THIS WINTER ...
Although there is little doubt that the ENSO event (La Nina and El Nino) events are somewhat is over hyped... the fact of the matter is that ENSO events are major players and MUST be considered in any attempt to make a seasonal forecast. ( The warm water events ....popularly called El Nino can also be referred to as warm ENSO.... while the cold water events .... La Nina .... is referred to as cold ENSO events).
This map (fig 1)refers to the area of the world where ENSO events ( El Nino / la Nina) occur. There are two agencies within the US that have the official responsibility to monitor the ENSO region -- CDC ( climate Diagnostic Center) and CPC (climate Prediction center). The ENSO region consists of several sectors .... ENSO 1+2 ( 1.2) ENSO 3 ENSO 4 and ENSO 3.4. Officially an El Nino or La Nina event is declared when the SSTA (sea surface temperature anomalies) have reached a certain level for a 3 month time period over the ENSO region known as 3.4 .
REGION 1 and 2 is situated right along the Peru coast just SOUTH of the
REGION 3 is the Red box area along the Equator.
REGION 4 is the Yellow area which extends along the Equator out past the Dateline.
REGION 3.4 is area shown by the THICK BLACK LINE .
Also you need to know that there are several sources for getting the latest data that meteorologists use for SSTAs in the various ENSO regions.
Two sites provide weekly updates: From CPC ... http://www.cpc.ncep.noaa.gov/data/indices/wksst.for and this site from the Australians http://www.bom.gov.au/climate/enso/indices.shtml (I strongly prefer the Aussie data)
While the La Nina of 2007 was slow and somewhat delayed in getting underway it has rapidly map up for lost ground in the weeks of OCT and NOV and is now as of Mid NOVEMBER 2007 clearly a Moderate garden variety La Nina. The real question is whether the La Nina will reach STRONG threshold criteria during the Winter months OR will the Moderate la Nina reach its peak in Mid DECEMBER 2007 then begin to decay in the 2nd half of the winter ...in manner much like what we saw with the Moderate El Nino Last winter . A decaying La Nina in the 2nd half of Winter of 2007-08 would greatly increase the chances of seeing a 2nd half winter much colder than the CF is currently calling for.
WEAK vs MODERATE/ STRONG LA NINA EVENTs
These next three images will clearly show differing impacts between a weak La NIna vs Moderate / strong one with respect to temperatures. As you can clearly see there is a strong correlation between a weak La Nina event and colder than normal temperatures over much of the central CONUS and near Normal temps for the Ohio Valley and Northeast. On the other hand there is a much stronger connection are between Moderate and Strong La Nina events and large areas of Above and Much Above Normal temperatures for the Lower Plains ...Deep South.... Midwest.... and Middle Atlantic states. central...southern US.
Looking at ALL of Moderate and Strong La Nina events since 1950... and we have to include Strong La Nina event since it is possible that this developing La Nina will reach the lower end of the "STRONG" La Nina threshold at some point this Winter. This Image shows Temperatures from the Mean of all the Moderate and La Nina events looks like broken down by climate divisions
if we break this down by 3 Winter months we Get these temperature anomalies for Moderate / Strong La Nina events
These Images clearly show the hemispheric pattern at 500 MB for DJF. The areas of dark Blue and Purple show major height anomalies In DEC the signal is pretty strong that there is sort of mean trough over the eastern Third of the CONUS-- which can be
This next Link shows the large scale 500 MB pattern DEC JAN FEB (DJF) based on WEAK La Nina events.... (click on image for full view). We can see several features over the Northern Hemisphere. Note the Yellow and green areas...over over Greenland... over the Eastern Pacific and eastern Siberia. These areas show positive anomalies at 500 MB. The Dark Blue areas show NEGATIVE height anomalies... over Scandinavia... the central Atlantic and over Japan. They KEY feature is the Positive anomalies over Greenland and the negative Height anomalies over Scandinavia. This is why WEAK la Nina events often lead to seasonal or colder than Normal winters over the central and Eastern CONUS. Greenand note the se next three images will clearly show differing impacts between a weak La Nina vs Moderate / strong one with respect to temperatures
WEAK FEB LA NINA
These next two charts clearly show where the current El
Nino event is with respect to other previous events since the 1950s. This first
link shows you a chart comparing the current SSTA in ENSO region 3.4 the last 14
El Nino events and as you can see the current event is definitely in the weaker
category or weaker group of all 14 El Niño events.
This next map shows you a more reasonable and closer look
of the MEI of weak El Niño events since the early 1950s with respect to how this
current event matches up. You can see that the closest overall match appears to
be the 1963- 64 weak El Nino event... but all these events on this
chart .... were significantly colder and
snowier than normal winters for Much of the central and
eastern CONUS.... except for 1951-52
It is important to keep in mind 2 salient
points regarding this El Niño event. First we have never seen a El Niño event
develop in the month of August. Not once as is ever happened. Second ... last
winter... 2005-06 featured a weak La Nina event. If take a look at the history
of the El Niño events in the Winter which have occurred after a weak La Nina the
previous Winter we find a very significant fact in the database.
Which is this... Most of the El Nino events that have occurred after a WEAK La Nina the previous Winter has NOT reached Moderate El Nino criteria for more a than a few weeks. Let's take a look at this in a bit more detail. This chart shows is the CPC 3 month mean SSTA for the region of ENSO 3.4. I have highlighted in purple the five cases where we have seen a weak La Nina in a winter season that was then followed by SOME sort of El Nino event the very next Winter. They are
1957...1963...1968... 1986... 2001.
We can discard the 2001 event because after the weak La Nina died off the SSTA in ENSO 3.4 stayed flat the Winter of 2001-02.
1957 began with a weak La Nina that quickly moved into weak El Nino in the SPRING then reached moderate levels of +1.2c and +1.5c in the 1957-58 winter. However the 1957-58 El Nino is not a great analog match for this season because that El Nino began in the Spring of 1957.
1963 is as close to a perfect match as one can possibly have. After the weak La Nina died off in the spring of 1963 SSTA remained a neutral until the Autumn then only rose to +1.0C in ENSO 3.4... which is exactly the pattern we are seeing what these current El Niño.
1968 ... is also a good match to the current event... the El Nino reached +1.3c briefly in January of 1969 then began to weaken.
1986... is also a decent match for the current event. However the cold water in ENSO 3.4 in the Jan and FEB of 1986 was not really strong enough to be officially declared a La Nina
KEY POINT THE BEST 3 MATCHES WHICH MATCH THE CURRENT LA NINO IN THE ENSO 3.4 REGION are 1963.... 1968...1986... then 1957
ENSO FORECAST FROM VARIOUS CLIMATE MODELS
This next table provides some information as to how strong the El Niño event names become during the winter. FIGURE 1 is a breakdown the18 Member CFS climate model used at CPC ... which is run every few days
As you can see there is a general consensus among these
ensembles members of the CFS model that the warm SSTAs in ENSO region 3.4 will
reach a peak of 1.25 to near +1.50 degrees sometime in middle or late January or
perhaps very early February.... and then begin to the climate pretty steady pace
Figure 2 and three are the ENSO 3.4 region forecasts from
the ECMWF centre in downtown Europe...
with Fig 2 based on September 1 and FIG 3 based on October 1. He may importance of these two images shows that he knew right of the European climate model shows a very sharp drop-off in the SSTA in ENSO 3.4 region in the 2nd half of the winter.
And lastly we can see figure #4 which is a collection of 19 various climate models that forecasters can consider regarding the ENSO region 3.4. Looking at this image we can see that almost all the models show a significant drop-off in the second half of the winter with the warm SSTAs in this region and only 1 model briefly reaches +1.5C with the vast majority of the data showing a borderline WEAK/ MODERATE event.
This next table actually is a breakdown of all those individual models that we see here and I have highlighted or summarized like these forecast models are showing... and began only a 5 of the 19 models show SSTA in ENSO 3.4 reaching and HOLDING Moderate level.
CMB'S ENSO FORECAST
|ECMWF ENSO 3.4 Forecast||IRI CLIMATE
19 FORECAST MODELS
|REGION 3.4||SEPT 1||OCT 1||EARLY OCT|
DETAILED BREAK DOWN OF ALL 19 IRI CLIMATE MODELS USED IN FIG 4
|NASA GMAO model||1.2||1.3||1.3||1.2||1.1||1||0.9||0.8||0.6||Moderate|
|NCEP Coupled Fcst Sys model||1||1.2||1.4||1.5||1.4||1.2||1||1||Moderate|
|Japan Met. Agency model||0.6||0.6||0.5||0.4||0.3||weak|
|Scripps Inst. HCM||0.9||0.9||0.9||0.8||0.7||0.5||0.3||0.2||0.1||weak|
|Lamont-Doherty model||0.9||1||1.1||1.1||1.1||1.1||1.1||1.1||1||weak/ Mod|
|POAMA (Austr) model||0.5||0.7||0.8||0.9||0.9||0.9||0.9||weak|
|ECMWF model||1.1||1.1||1.1||weak/ Mod|
|SNU (Korea) model||0.9||0.9||0.9||0.9||0.8||0.8||0.7||0.6||0.5||weak|
|ESSIC Intermed. Coupled model||0.5||0.6||0.6||0.5||0.5||0.5||0.5||0.6||0.7||weak|
|ECHAM/MOM||1.2||1.3||1.3||1.2||0.9||Moderate falls off to weak late in winter|
|COLA ANOM||1.3||1.3||1.2||0.9||0.6||0.4||0.2||0.2||0.1||Moderate falls off to weak late in winter|
|Average, dynamical models||0.9||1||1||0.9||0.8||0.8||0.7||0.6||0.5||WEAK|
|NCEP/CPC Markov model||0.9||1||1||0.9||0.8||0.7||0.6||0.6||0.5||weak|
|NOAA/CDC Linear Inverse||0.8||0.7||0.7||0.7||0.6||0.5||0.4||0.3||0.3||weak|
|NCEP/CPC Constructed Analog||0.8||0.7||0.6||0.4||0.3||0.3||0.3||0.4||0.4||weak|
|NCEP/CPC Can Cor Anal||0.6||0.6||0.6||0.6||0.6||0.6||0.6||0.6||0.6||weak|
|Univ. BC Neural Network||1.1||1.4||1.4||1.5||1.6||1.4||1.2||1||0.9||MODERATE|
|FSU Regression||1.2||1.2||1.2||1||0.8||0.5||0.3||0||-0.2||Moderate falls off to weak late in winter|
|TDC - UCLA||1.3||1.3||1.1||0.9||0.6||0.5||0.4||0.3||0.3||Moderate falls off to weak late in winter|
|Average, statistical models||0.9||1||0.9||0.8||0.7||0.6||0.6||0.5||0.4||WEAK|
|Average, all models||0.9||1||1||0.9||0.8||0.7||0.6||0.5||0.4||WEAK|
The folks over at CDC - Climate Diagnostic Center have developed a More complete way of measuring ENSO events .... be it a El Nino or La Nina event. The MEI or Multivariate ENSO Index (MEI) measure all El Nino and La Nina events on six main observed variables over the tropical Pacific. ( sea-level pressure... zonal surface winds... meridian surface winds.... sea surface temperature... surface air temperature... and total cloudiness as a fraction of the sky
FULL DETAIL and a better overall image of ALL the MEI data since 1950 can be seen here http://www.cdc.noaa.gov/people/klaus.wolter/MEI/
However for ease of comprehension I have created this table of MEI values from January to November 2006. what I am searching for here is NOT a exact numerical Value match but the overall trend .
2007 MEI VALUES FROM JAN TO NOV 6
Note the MEI values were moderately NEGATIVE in the Winter and Spring (hence the weak La Nina)... then rose to NEUTRAL and steadily But NOT rapidly rose into weak El Nino levels in JULY AUG SEPT. The OCT 2006 value is right on the border between WEAK and MODERATE El Nino...
Here are the 4 analog years that closet match with what we have seen with this CURRENT MEI . Over on the far right columns I have made a few comments for your consideration
|-0.426||+0.88||+.388||+.886||+.755||+0.958||+1.104||+1.138||+1.091||+1.111||+1.19||So-So... MEI rose to above +1.0 in AUG 1957|
|1986||-0.304||-0.225||+0.040||-0.103||+.318||+.311||+.387||+0.713||+1.093||+1.012||+.856||+1.186||2ND BEST ... ROSE TO +1.012 in OCT 1986 matching the OCT 2006 value|
KEY POINT THE BEST 3 MATCHES to MEI OF 2006 .... 1963 1986 and 2002
HURRICANE OF 2007 --
DOES IT MEAN ANYTHING FOR THE WINTER OF 2007-08?
You know what's really interesting? Last year when we had that super active hurricane season there were an awful lot of private forecasters out there ranting and raving about how the 2005 Hurricane season was somehow connected atmospherically to what the upcoming Winter might hold for the eastern half of CONUS. Now that we have had a sub active hurricane season... suddenly there are not a lot of people talking about the hurricane connection and what it might or might not mean for the winter.
Isn't that curious?
Since there is not a lot of speculation about what the 2006 hurricane season might mean for this coming Winter across the CONUS... I won't spend a lot of time on this aspect of the forecast. However it one point I do want to make is that there is significant research out there which shows SOME correlation between Hurricane activity over the southeast US and what that means or implies for the following winter.
You see the problem was that last year these private forecasters that were banging the drum about Winter of 2005-06 took that research and misused it. Instead of using the actual research which does lend some support to the idea that active hurricane season over the southeast US has implications for the overall pattern in the following winter... they took this data and asserted that ANY sort of above normal activity in the Gulf Mexico has implications for the overall Winter pattern. That of course is 100% BS... However IF the goal was to get an awful lot Media attention and get yourself on CNBC while Natural gas and Heating oil prices rise.... then that strategy was successful .
Again keeping in mind the original research... we have seen some Hurricane seasons where there has been decent a cluster of over the Southeast CONUS and the following Winters have been significant. The hurricane season of 1995 which featured a lot of activity in the tropics but saw numerous Tropical Cyclones constantly turned away from the East Coast ....because the mean trough position was located over the East Coast in the autumn of 1995. Likewise we sought awful lot of activity into Florida and the Southeast states in 2004 in the winter of 2004 --05 with reactive as well.
This year while we have not see a lot of activity... they were three of the 9 named storms that developed in eastern Gulf OR off the FL coast that passes through a very close Florida and /or parallel the Southeast US coast... ALBERTO BERYL and ERNESTO. There also several Tropical Cyclones which were turned out to see in the central portions of Atlantic. First let me show why this idea is crap and then why it was done.
THE NAO FACTOR
Again keeping in mind that it is my goal to convey information without getting bogged down in Too much detail...
The NAO or North Atlantic Oscillation is one of the major modes of variability of the Northern Hemisphere atmosphere. It is particularly important in winter, when it exerts a strong control on the climate of the Northern Hemisphere. There are several manifestations of the NAO. Basically without getting to technical the NAO a particular jet stream configuration which exists over the regions of the Northern Hemisphere from eastern or northeastern Canada to Greenland and over towards Iceland and Northwest Europe.
Sometimes you'll hear the phrase 'High Latitude blocking' and if this is occurring over eastern Canada or Greenland for example this phrase might be referring to a negative phase of the NAO.
Arguably the most difficult aspect of any WINTER forecast for the central and eastern half of the CONUS is trying to predict or figure out what he and Io is going to be doing this winter... what percentage of the time will this critical feature be in the NEGATIVE phase ( colder and stormy pattern for the central and eastern US as well as se Canada) or POSITIVE PHASE (milder and less stormy).
SOME LINKS FOR THOSE WHO WISH TO KNOW MORE
This image is the latest sea surface temperature anomaly map for the entire world which comes from the Unisys web site... and it shows some very interesting things.
To begin there is a noticeable area of very warm SSTAs
located east of the Newfoundland in the Northwest Atlantic which stretches up
into the Davis Straits and east over towards the Northeast Atlantic. This pool
of very warm water has been there since the Summer but back then this pool of
very warm water was located significantly further south. In addition we can see
some more temperatures that are actually below normal off the Southeast coast of
the CONUS and sea surface temperatures are between Iceland and Greenland.
Research has shown that this sort of sea surface temperature anomaly configuration ( in the weather biz this is called the North Atlantic SSTA tripole) is supportive of a sustained negative phase of the NAO. This is not by any means a guarantee but there is some correlation between sea surface temperature configuration like the ones we currently have in the North Atlantic and fairly long intervals of the NAO staying in the negative.
In addition as I mentioned about with the drought pattern over the Plains states .... the location of the Ridge over the Plains supports the mean trough position over the East Coast which in turn does favor some sort of positive height anomaly over the Northwest Atlantic and /or Greenland.
If we look at the longer-term trend will see that the NAO has been in the negative phase for the most part since late July early August with only a few brief intervals where the NAO went positive.
Keep in mind there are a lot of government and private forecasts which attempt to predict me and we'll phase for either a portion of the winter or for the season as a whole. Most of their forecast have not as bad but wretchedly so in this may explain why so many of the last few went to forecast had been so bad across North America.
For example the British issue a "experimental" NAO forecast every Autumn for the following winter. As you can see from this chart... provided by the UKMO... they have been making these NAO forecasts for many years. The problem is that the British NAO seasonal forecast has really really wrong for many years. In fact I cannot recall the last time the British have gotten the NAO phase even remotely correct over the last 10 years.
Looking at the last several years of this chart since
2000... if the British went out of their way to intentionally forecast the WRONG
phase of the NAO they could not do a better job!!! Of course that Is not what
they are trying to do and they should be applauded for making an effort. However
in my opinion by putting out NAO forecasts which well SUCK... a lot of private
forecasters refer to the well-known British NAO forecast as is
some sort of reliable piece of data when as you can see from this chart the
British NAO is absolutely worthless.
WXRISK VIEW: While many
see the SSTA set up for
the Atlantic Ocean as NOT ideal for
sustained intervals of the negative
phase of the NAO I see some promise. Many
forecasters assume that there can only be one particular manifestation of the
negative phase of the NAO... which is called the Greenland Block. However
sometimes you can get a
-NAO manifestation that shows up as a blocking pattern over the Davis Straits... or northeastern Canada or northern Québec. Indeed we saw that several times during the months of September and October. And the strong pools of very warm SSTA in and around the Davis Straits and of the coast of southeastern Canada strongly supports the idea of a westward positioned blocking pattern developing over northern Québec or the Davis Straits from time to time this winter. I do not see a " ideal" SSTA configuration at this time although it would not take much to change the Atlantic SSTAs into a pattern that would favor sustained -NAO.
Over the last 10 years there has been a significant amount of research done on a climate pattern that is called the PDO in the weather biz. The PDO or "Pacific Decadal Oscillation" a long-lived climate pattern that exists over the northern Pacific Ocean.
The PDO 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. Why is this important? Again research has shown that large areas of warm and cold water pools called SSTA couplets STRONGLY affect the Jet stream pattern and the positions of Ridges and troughs within the Jet Stream over the Pacific and western North America.
This is diagram shows you the Two phases of the PDO... the BLUE color represents very cold SSTA... the Green cool SSTA.... the RED color very warm SSTA and the Yellow warm SSTA.
The map below explains HOW and why the PDO affects the pattern across North America. Click on the Maps to see the Full size. As you can see when the PDO is in the Positive or WARM phase... the warm sea surface temperature anomalies along the West Coast North America strongly supports a ridge developing over the western portions of the continent and locking this Ridge in place. Of course if you have a Ridge over the West Coast then downstream you have to have a trough.... (for every action there is the equal opposite reaction)... which in this case is over the eastern third of the US. This pattern is known as the +PNA and it is the classic signature for a cold weather pattern. The arctic air masses from the Arctic regions and northern Canada follow the Jet stream down into this trough which results in sustained intervals of below row temperatures cold water. On the West Coast the Ridge of High-pressure means clear skies very little storminess and Above normal temperatures.
However the opposite is true what we had a negative or cold phase of the PDO. In this case the warm water is located out in the Central Pacific Ocean and cold water develops along the West Coast North America. This results in the jet stream developing a trough along the West coast... and of course downstream a Ridge develops over the eastern half the US. This sort of pattern results in a very cold and stormy West Coast with areas such as a Seattle and Portland saying snowstorms in the very strong cases out of the negative phase PDO... and the central and eastern US saying below normal precipitation and above mobile temperatures.
The correlation between the temperature patterns across North America and PDO phase is very strong and it's very hard to ignore.
The PDO also has some impact on El Nino / La Nina events. While the PDO and ENSO events have similar climate "fingerprints"... they have very different behaviors in time. For example a phase of the PDO can persist for 20-to-30 years while typical ENSO events persisted for 6 to 18 months. Within that 20-30 year PDO cycle one phase is more favored than the other. For example when the PDO is in the "Negative Phase" most of the time the PDO will run in the Negative pattern with just a few instances of PDO developing a Positive Phase... and vice versa. In additions the PDO directly affects the ability of the El Nino or La Nina event to reach the STRONG category. When the PDO is in a negative phase the El Nino event trend to be weaker while La Nina events are stronger. On the other when when the PDO is in the Positive or warm phase the El Nino events tend to be longer lasting and stronger while La Nina event s are weaker
Again if we take a
look at the latest SSTA map
we see large areas of cold water located off the Baja California coast and
SSTA that close to neutral or slightly below normal over much of the Northeast
Pacific-- off the West coast of Canada -- and north of Hawaii.
In fact in the northern Pacific the only areas of really large bodies of warm
water exist in and around Japan. The overall sea surface
temperature pattern or configuration is clearly indicative of a negative phase
PDO ( hereafter called a -PDO). However it is not a
strongly negative phase like we saw last year which means that it's possible
during the middle or second half the winter the PDO phase could change... from
negative to positive. In order for something like that to occur... they would
have to be a significant increase in areas of warm either over the Central
Pacific that moves eastward or developing over the Eastern Pacific near the
North American coast. Began at this time there does not appear to be anything
indicating that might be the case but because we are dealing with a weak -PDO
phase such a change could occur in the second half of the winter.
Again keep in mind that -PDO means a constant stream of Pacific Energy bombarding the West Coast and it also restricts the ability of cold air pour southward from Western Central Canada into the central and eastern portions of the CONUS. However since this -PDO is a weak one ... there is a high probability that the Pacific Jet stream will split into two branches on the West Coast. This sort of split in the jet stream pattern is an indicator that forecasters look for that the pattern is about to become stormy.
The quasi-biennial oscillation (QBO) is a Band of High level zonal winds found over the Equatorial at very high altitudes ( even above the Jet Stream). It is a very well known periodic oscillation in atmosphere. The has been a lot of research done over the last 10 years that shows the QBO has significant impact of overall climate patterns ... as well as Winter Weather patterns as well as the Hurricane season. The period of the QBO "oscillation" is about (a little over) two years. The QBO has two "phases" with occur within the 1 Oscillation cycle-- the Easterly or NEGATIVE phase and the WESTERLY or Positive phase. Within the meteorological community the QBO is used heavily by SOME as a key ingredient to figuring out what the Winter pattern across North America might be... while other forecasters dont think its all that relevant.
In my opinion However much of the discussion is mis-directed towards How and why the QBO is important For example it has been asserted that during the Winter season....the Eastern half of the US is often cold and snowier than Normal when the QBO is in Westerly or Positive phase while others have asserted that the Easterly or Negative Phase is better for colder and snowier Eastern US winters.
This LINK has the QBO data going back to 1948. It is my position that the QBO index is NOT a indices that directly relates to the overall pattern per se ...be it Winter... Spring...Summer or Autumn. The reason why I think the QBO is important is that it tell us what the Pacific Jet is going to be doing over the central and eastern Pacific. Good weather forecasters should be willing to tell you that if you get the West coast of North America wrong ... you get EVERYTHING else-- the Rockies to the Plains to the Midwest to the Deep South and East coast wrong as well. Perhaps this explains why there are often so many snow and cold forecasts for the eastern US out there that are so often wrong or over hyped.
It is My contention that a East or Negative Phase of the QBO as we go into the Winter months correlates to a more active and stronger Pacific Jet stream... which means more rains and storminess for the Pacific NW and West coast and a Ridge over the SE or East coast.
A QBO value that is strongly positive as we go into the Winter months ...say above +10.0 or higher almost always implies a lack of cold air build up in Canada and a Milder winter for the CONUS .
A QBO value that is near zero as we go into the Winter months --- say from +5.0 to -5.0 implies a Pacific Jet that is weak and favorable for all sorts of large scale pattern shifts and changes -- called pattern amplification and de-amplification ( lots of storms and blocking patterns) .
Here are the current QBO values for 2005.
2007 QBO VALUES FROM JAN TO OCT
The KEY point to consider is that IF the
current QBO Phase stays strongly positive into the winter in any probabilities
all saying significant cold air outbreaks or a colder than normal overall
pattern would be significantly reduced. If on the other hand the QBO phase drops
towards neutral then the overall pattern becomes much more promising for
significant winter weather over much of the nation as well as the chances for
more significant cold air outbreaks.
If you scan all the QB0 data and you look for QBO events which were strongly negative... reached NEUTRAL ... then PEAKED ... and dropped back to NEUTRAL ... you can plot how long it takes for the positive phase of the QBO to run its course. That cycle takes anywhere from 10 to 16 months.
1994-95 had a QBO that was at one strong negative-- minus 25.00 or lower. Once the QBO
reached Neutral with QBO took 12 months to reach the Peak Positive value then drop back to Neutral.
On 1996-7 the QBO was a strongly negative one -- that dropped to -25.00 or lower. Once the QBO reached Neutral... it took 11 months to reach its peak then back to Neutral.
1984-85 the QBO was a strongly negative one -- that dropped to -25.00 or lower. Once the QBO reached Neutral... it took 16 months to reach its peak then back to Neutral.
The current QBO phase became neutral in March 2006... it is now in its 9th month ( November 2006). It is probable that some point in the winter or specially the second half the winter the QBO will rapidly breakdown with which neutral. This again leads support to the overall idea that the second half the winter was going to be significantly worse than the first portion of winter 2006 --07.
As for a QBO analog... let me emphasize that we are not looking for an exact match with respect to the numerical values per se but the overall QBO trend. What I am looking for is a analog to this particular pattern... a QBO that was very strongly negative ( -25.00 or lower) last winter... that became neutral by March 2006... that rose to +10 or higher in May 2006 and held close to +10 since then.
|1957-58||-20.06||-17.24||-14.02||-9.27||-5.91||-2.30||+3.15||+7.07||+10.09||+11.69||+10.71||+8.30||NOT a good match Summer 1959 to Summer 2006|
|-11.58||-6.98||-2.01||+1.80||+3.21||+4.05||+6.30||+8.36||+10.46||+10.11||+7.35||NOT a good match Summer 1957 to Summer 2006|
|1966-67||-21.90||-17.14||-11.07||-2.33||+2.16||+5.42||+7.47||+7.63||+9.23||+11.00||+11.74||+13.26||too strong going into winter of 1966-67 when compared to 2006-07|
|1971-72||-10.67||-3.67||+0.91||+3.75||+6.77||+8.28||+8.8||+8.34||+8.95||+8.47||+8.47||+9.10||BEST ... note the Plateau of Pos value between +8 and +9 all summer and Autumn 1971 ... similar to Summer Autumn 2006|
|1975-76||-16..0||-15.39||-13.04||-5.12||+1.18||+4.47||+7.41||+9.06||+10.25||+10.65||+11.27||+10.95||Good match... note the Plateau of Pos value between +10 and +11 Autumn 1975|
KEY POINT THE BEST 3 MATCHES to QBO OF 2006 .... year 1971 1966 and 1975
SNOW COVER NORTH AMERICA
Snow cover is one of those nebulous qualities that forecasters look at in the months of October & November in Canada. The Premise is that when you have early or heavy snow cover over a good portion of Canada there is a tendency to build colder and longer lasting arctic air masses which can then plunge into various portions all of the CONUS during the Winter months.
There is data which shows a very strong correlation especially east of the Mississippi River to mean temperatures during December January and February and snow cover in Canada. When the snow cover in OCT and NOV is above Normal Temperatures East of the Mississippi river tend to run Below or Much below normal.... and when snow cover in the months of October November is Below normal in Canada temperatures east of the Mississippi river tend to run milder than Normal.
That being said simply having early and/or heavy snow cover in the months of October and November over Canada does not necessarily mean that you are going to have a cold and/or Snowy Winter over the central and eastern US. It just increases the chances that such a scenario COULD happen... the tendency to produce colder and longer lasting air masses is there. However if one were to look at the data from the Autumn of 1977 snow cover was below normal in Canada during the months of October November and yet that turned out to be one of the cold winters on record. On the other hand there was above normal snow cover in the months of October November 1978 in Canada and we had a very cold and stormy winter that followed in the lower 48 states.
The only thing can be said with any degree of certainty in my opinion regarding snow cover is that if you have October and November with below normal snow cover the odds are increased that you will have significantly LESS cold air outbreaks plunging into the CONUS. For example the super warm winter of 2001 --02 saw much below normal snow cover in October and November over Canada. The implication here is that when the cold air masses formed and moved south they rapidly modified as they came southward due to lack a snow cover in southern Canada during the heart of the 2001-02 winter.
To be certain we got off to a very weak start with snow cover over Canada in October 2006. The data does show that snow cover for Canada was below normal but we did see significant increases in the snow cover as the month came to a close. We can see that clearly here...
and the differences in snow cover from the first week October when compared to the last days of October are quite impressive.
This increased snow cover continues through mid-November right up to the US Canada border. The snow cover build up in Siberia is Impressive -- Much above Normal there.
Now typically what happens with Moderate or strong El Niño pattern is that the large Upper Low develops over Alaska near the Bering Sea... and from this position the strong jet stream comes around the Upper Low and slams into Western Canada. This ends up destroying the snow cover in Western Canada as well as preventing any sort of cross Polar flow developing from Siberia into North America. This is just one of the ways (but a overlooked way) that a strong or moderate El Niño ends up affecting the overall pattern North America
However with a weak El Niño the entire pattern gets displaced. The vortex that in a strong / moderate El Niño is over the Bering Sea often gets displaced to the east in a weak El Niño... and is often found in the northeastern Gulf of Alaska near the West Canada Coast. When this pattern occurs Western portions of Canada and the Pacific Northwest see a lot of precipitation... but much of it falls as snow since the very deep Vortex is located on the western Canadian Coast and that brings in some very cold air masses. In addition the weak El Niño position ends up increasing snow cover over much of Canada even while it provides a mild conditions for much of the CONUS.
Thus when the Jet stream decides to split into two branches the cold air is located very close to the US Canada border and the Arctic outbreaks can occur with a lot more frequency.
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