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08-09 Winter Forecast

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2008-2009 Winter Forecast

 

Preface

 

My methodology for doing a winter forecast is as follow… Weather is wild, its constantly changing and there for the same rules or methods that work in one years winter outlook, won’t necessarily work for another year’s outlook depending on the strength of certain factors.  For example if we were facing a raging La or El Niņo not as much emphasis should be placed on conditions in the Atlantic. Also in neutral or el Nino years I look at the fall weather patter more than I do for a La Nina of moderate strength or greater.  There are certain tools that other forecasters use such as the QBO, from my research its hard to nail down true analogs due to combining a certain QBO value with its correlation to whatever the ENSO state is.  The sample size just isn’t big enough.

 

The factors that are going into this forecast, In terms of analogs:

 

1)         El Nino 3.4- Current Conditions vs. past analogs

 

2)         ENSO Transition- Years in which, in this case we were exiting a mod-strong Nina into neutral (nina lean) conditions.

 

3)         NAO regime- the type of pattern that we are seeing in NAO conditions over the long term and where we should be heading based on trend

 

4)         Atlantic SST- Analogs with similar conditions found in the Atlantic

 

5)         Fall Weather Pattern- Temperature Analogs for Oct

 

Each of the analogs found are weighted based on these 5 factors.

 

*- It should be noted that all analogs are neutral type ENSO’s with a little more leniency from weak La to weak El 

 

Pre 1946 data loses one of its weighting numbers due to age and possible accuracy of data

 

Snowfall analogs

 

For this particular season… The analogs must have conditions that correlate to the NAO regime or Atlantic SST’s (remember all analogs are neutral ENSO’s anyway).  Only exception to the SST/NAO rule is the Fall Analogs due to their heavier weighting in this potential winter pattern.

 

 

El NINO  3.4

 

 

The first place to start is El Nino 3.4 index. Our analogs are in the chart above…

2000-2001

1974-1975

1985-1986

1989-1990

1976-1977

1971-1972

 

Next Subject Is The Transition In ENSO from season to season... mod strong la- to neutral- to Neutal, Nina lean

 

 

 

There are 6 occasions where we have exited a mod-strong Nina and floudered through neutral conditions in the fall to end up with neutral- nina lean winters…

 

2000-2001

1989-1990

 

These two now receive a weighting of 2 due to their showing up in the Nino 3.4

 

Joinging them in the analogs are:

 

1968-1969

1950-1951

1946-1947

1939-1940

 

NAO REGIEME

 

As can be seen in the chart below there is an overall pattern to the changes seen in the NAO, that usually spans decades.  In other more updated charts it can be seen that we are entering a period for a –NAO to rule the roost.  And this year we have spent a majority of the time in - NAO conditions.  This puts us in line with decades lke the 40's and 60's which were quite cold and or snowier winter decades.

 

 

 

In looking for NAO analogs first we’ll take clear –NAO matches

 

2000-2001 comes up again and is now a 3

 

1950-1951 1939-1940,1946-1947 and 1968-169 are now a 2

 

Joining the analog list is 1976-1977 at a 1

 

Atlantic Oct SST (Cool- Warm- Cool closest Matches)

 

Looking at Atlantic SST’s for the month of Oct again 2000-2001 comes up (now a 4) and sure to raise a few eye brows… 1995-1996 (In fact if you look at the current SST and compare to Nov it’s even closer than Oct’s)… Remember in 1995 at this point the Nina was just getting rolling (overall).  What I am looking for is the cool Caribbean, warm mid latitude and cool North Atlantic pools

 

Current

 

Oct 2000 best match and Oct 1995 second best match, this takes the 2000-2001 winter to a 4 weight and the blockbuster 95-96 is now a one, but with weight in the snowfall analogs.

 

 

Fall Pattern Temperature Analogs For Oct 2008

 

(Cold Oct's in Neutral Enso favor snowy/coler NE winters)

 

OCT 2008

 

 

 

 

October Analogs

In Neutral or weak signal years, the fall weather pattern, particularly October can be indictor of how the following winter may end up.  Now trying to find exact matches in nationwide anomolies is quite difficult but surprisingly the Oct 1993 pretty darn close and Oct 1977 isn’t too far off in terms of locations of different anomolies (generaly speaking)

 

MY WEIGHTED ANALOG LIST FOR WINTER 2008-2009

So the following is the list of analog years in decending order by their weighting number

(Yellow Highlights Indicates Use In Snow Analogs)

 

*1976-77- by all rights should be used in the sow analog at least according to my threshold but the rapid ascension towards El Nino conditions takes it out of the running as it’s a mitigating factor on the Atlantics dominance

 

 

 

Putting It All Together Let's Take A Look At A SnapShot Of The Winter As A Whole...

 

Temps:

 

Any winter lover is going to love seeing that map... colder than average over the eastern 2/3 of the US... Well that's usually a good place to start if you want a "good" winter.

 

Now lets look deeper at each month before spelling out my forecast.

 

December

 

This is the month that sets the tone for the winter just as it did in 95 and 00... It will be the coldest month and there will be plenty of chances for storminess on the EC.  This period is close enough right now to look at some modeling and some of the other tools we can look at.  It looks like after Thanksgiving its game on.  Most of the month will be cold there will be battles with warmth toward the end of the month.  But the die has already been cast

 

 

My Dec Maps:

 

 

January

 

This is my make it or break it month as is usually the case for all forecasters, It is my indication that due to a better NAO signal that we will shake off the shackles of the last several January's and this month will see much more cold and snow than in years past. There will be periods of warm battles with the cold however, but not warmth in dominance, it will be these battles that could produce big storms particularly mid to late month before a true flip to warm that is coming.

 

 

My January Maps:

 

 

February

 

The month that will be the warmest in my estimation as the cold reloads in Canada and into the Central US.

 

 

My February Maps:

 

 

*** Bonus Prelim March Outlook Maps

 

WINTER SNOW ANALOGS

 

Reasoning was covered above in the list of weighted analogs and in the preface.

 

Fall Wx Pattern Snow Analogs...

 

 

Other Snow Analogs

 

 

It should be noticed fairly quickly that all of these winters featured a snowy northeast winter, some were coastal years, others... I-95 ers and some just Interior from the big cities.  But all were rockem sock em winters overall... So with fairly high confidence my snowfall outlook is below...

 

*note white areas are 120%-150% NOT 100-150%