2011 - 2012 Winter Outlook.

Hi it's Rebecca, I've been meaning to post this for the last 3 weeks. But things and events interfered. Anyway, I thought I would take the time to put it together today. This outlook is based on several key factors: the ENSO (El Nino/Southern Oscillation),the Pacific Decadal Oscillation (PDO), the North Atlantic Oscillation (NAO), the Arctic Oscillation (AO), past years that had a similar pattern, and Snow Cover in Alaska, Canada, and Siberia. I even looked at solar activity.

Before I get into the specifics of the outlook, I want to spend a little time explaining what an outlook is. First a winter outlook is not a forecast. A forecast deals with specific weather events such as storms.  With a forecast you look at data, in order to figure out precipitation type, severity, and timing of a storm. Where as an outlook talks about how the winter pattern will set-up, it attempts to show where the major storm tracks will set-up and how the winter will trend. It will not tell you how many Blizzards, Nor'easters, or ice storms there will be, or when they will occur.

The winter pattern starts with a strengthening jet as it makes it's migration south. Something we're just starting to see. How the jet acts and sets up effects how the troughs will act and move during the winter. Most agree that the winter of 2011-2012 will see the return of a moderate La Nina. The long range models are supporting this idea, more or less. If this is the case, then the key to our upcoming winter will be the return of some strong high pressure blocking over northeastern Canada. The good news is the Euro long-range does not show much if any high pressure setting up over NE Canada. The Bad news is Last year's Euro long range showed some blocking but nowhere near as strong as what actually setup . Last year was a La Nina and we all know how that turned out. Now if the Euro is right we won't have a block setup this would mean just to our north in Ontario and southern Quebec would see tons of snow; while we had a warmer than normal winter with more or less normal snowfall. Now back to the outlook.

For those who don't want to read the science, you can skip to the summary at the end of the post. However, if you do so you will miss a lot of interesting information and how I came to my conclusion.

The Factors:

Factor #1: ENSO:
Probably the most talked-about index. You always hear the words El Nino and La Nina thrown around. The positive phase, or El Nino, is when the winds at the equator are pushed west to east. These keep sea surface temperatures fairly warm. A negative, or La Nina phase, is when the winds reverse. This allows for waters to be "dragged" from east to west, thus pulling to the surface, or upwelling, cooler waters just under the surface around South America.  A weak to moderate  La Nina winter will be the case for  Winter 2011 - 2012. Historically, La Nina favors a warmer than usual fall. As we have seen so far this year supports this idea. Last year’s La Nina November brought much less snowfall than average. The lakes stayed on the warmer side heading into December. Weak to moderate La Nina patterns tend to give more snow to New England, New York State, and the interior mid-Atlantic. La Nina is a little more transient, usually producing a ridge of high pressure across the West which drives the jet stream north, and then it dives down across the Midwest. Up here in the Northeast our weather will depends on how the storms track along the Jet and how the trough axis sets up. How much snow we get really depends on the exact track of individual storms. A difference of just 60 to 100 miles can make a huge difference in snowfall amounts. However, this is just the first factor.
 

 Factor #2 the PDO:
To put it briefly, PDO is another sea temperature phenomena. It has two phases, a warm phase (positive) and a cool phase (negative).  The other oscillations have the same phases. The warm and cool phases in the PDO last a lot longer than El Nino and La Nina, typically lasting 10 to 40 years - with a few shorter intervals occasionally in between. The cool PDO phases have been linked to cooler temperatures, and vice versa. I feel we are at the beginning of a longer cool PDO phase. The PDO focuses on the northern portion of the Pacific Ocean, towards Alaska and the Aleutian Islands. It accounts for Northern Pacific Ocean temperatures.  Since 2008 the PDO has flipped back into a negative cold phase. When the PDO is in a negative phase the Jet tracks north of Alaska, which sets up a trough axis that lines up from Great Lakes down in to Alabama. This kind of track sends a lot of storms into the Great Lakes and Midwest.  When the PDO is in a cold phase the Great Lakes and Ohio Valley into New England tend to see below normal temperatures. The PDO was in this same phase for the  winters from the 1950’s, 60’s and 70’s. I will get more into past years in a little bit. The main thing to remember is: on average, we see more snow during a negative phase than during a positive phase. That's it for the second factor.

Factor #3 the NAO:
There will be a couple of wildcards this winter. The NAO will be one of them. This oscillation is quite different than the ENSO and PDO. Because it's not solely driven by ocean temperatures; which makes it extremely hard to predict.

The top image shows what happens when there is no block in the East, allowing storms to track generally West to East across the United States. This is call a flat pattern

The bottom image shows how a negitave NAO effects the storm track. When the NAO is negative, it sets up a block of the jet stream, making it more amplified, and storms are forced up the coast as potential blockbuster storms. This is also known as the "Greenland block" since high pressure blocking sets up near Greenland. When the NAO is negative the overall pattern is more unsettled weather , frequent and sustained cold snaps, and above normal snowfall.

The NAO this past month has been positive much of the time, and combined with a strong ridging and -PNA out West, it has resulted in warmer weather. In the near future, I see the NAO returning to negative, and will alternate from positive to negative this winter, but I think the primary phase will be negative for the most part, especially the first two thirds of the Winter.

Factor #4 the AO:
This is the other wildcard. The AO takes place over the North Pole.  This flow from the Arctic can and often does work hand in hand with the NAO. The Arctic Oscillation (AO) has a significant influence on winter weather in the U.S. Especially, the northern and eastern U.S.  By this I mean the AO plays a big part in how much cold air will get pulled into systems in the Lower U.S. The AO was at a  record low for the 2010 -2011 winter season.  Because of that many places saw well above average in snowfall. When the AO is negative storms will take a more northern track. The AO has been on the positive side for a little while. However, it's starting to show signs of a tilt to the negative side.  I think the AO will be negative for the first half of this winter (Mid Dec- end of Jan) then starting to turn positive sometime in February. in my opinion, the AO is the hardest oscillation to predict; because it changes so often.  The past two winters have produced times of very negative values. This resulted in  very snowy winters.

Factor #5 snow cover:
One of the things I do in trying to figure out what an upcoming winter will be like; is look at the extent of snow and ice in the Arctic. I start looking at the snow cover in Siberia in October. In November,  I look at the snow cover in both Alaska and Northern Canada.

The images below shows the current snow cover in Alaska, Canada and Siberia along with a comparison to this time last year.

From the images above I can see three very important things:

1) The snow pack in Canada is creating a cold air pocket, you can call it the  "icebox effect" This will cause colder than average temperatures in the Northern half of the US during the typically colder Winter months. The snow pack in Siberia is quite extensive right now.  Snow cover is important to factor into a winter outlook, because it establishes a cross Polar flow. By this I mean the Arctic cold over Siberia will be able to flow over the North Pole/Arctic region into Central and North Central Canada... and right now we don't have that. If there is no cold Arctic air in Canada, which is the case right now, it can't get cold no matter how strong the cold looks to be in long range guidance. So the build-up of serious deep cold Arctic air in Canada is a huge deal.

2) As I've been saying in my weather page, once winter decides to make an appearance Winter will come in with a vengeance once the pattern changes, and cold air in Canada can make it to the lower 48 and Northeast US.

3) From the look of things, I feel the Northern Hemisphere will be under the influence of a strong polar vortex (PV). this will only make things worse, it will help amplify the northern and Southern branches of the Jet.  Combine that with a -PDO, -NAO, -AO. now add in the ridging out West and the expected trough (remember 2011-2012 will have a --NAO and -AO) .... and look out. storms will be following one after another.

 
Factor #6 Solar
The study “Solar forcing of winter climate variability in the Northern Hemisphere”, led by a team of scientists in the United Kingdom, examined how weather patterns changed when the amount of solar radiation reaching the Earth rises and falls. The authors reached the conclusion of when solar activity is low; it produces colder winters in the United States and northern Europe and milder winters in Canada and southern Europe.

Link to the solar study

"The Sun has recently been in a quiet phase of its regular 11-year cycle, which coincided with three years in which the UK, along with other places in northern Europe and parts of the US, experienced cold conditions unusual in the recent record. But unusually warm weather was felt both further south, around the Mediterranean Sea, and further north in Canada and Greenland." - UK MET OFFICE

The solar minimum of 2008 is said to have played a huge role in the negative NAO that dominated the previous 3 winters. I've read that low solar activity leads to high latitude blocking. Solar activity has started to increase of late. But since the cycle runs for 11 years; I don't think the increase will be much of a contributing factor this year. So it's influence on the negative NAO will be negligible.

Nor'easters:

A Nor'easter is a storm characterized by a central low pressure area that deepens dramatically as it moves northward along the East Coast.  The heaviest snow in a Nor'easter falls to the north and west of the track of the surface low. Nor'easters can be classified into one of two categories, Miller A and Miller B

Miller A 's are what I call a classic Nor'easter, they develop primarily on the Gulf Coast or East Coast along an old cold front and deepen as they move north.  The "Superstorm of March 1993" is considered to have been a "Miller Type-A" storm.

Miller B's are a little different, they normally dump snow in the Midwest/Ohio Valley . As it approaches the Appalachian Mountains they lose their power and transfer it to a developing low on the coast.  

 

Above are images of Nor'easter's the top one is a Miller A and the bottom one is a Miller B.

If there are coastal storms, the Miller B pattern set-up will be more common than in a Miller A scenario in this type of pattern.

 Past Winters: 

Besides all of the above data, I looked at past winters. I am a firm believer in patterns. The ability to recognize these patterns is what makes a good forecaster. I looked at several winters over the last 60-65 years. I paid special attention to  second and third year La Nina's since 1950. I also looked at years that were neutral. when all was said and done, I came up with this  list of winters for analog years.

1950-1951

1955-1956

1961-1962

1974-1975

1975-1976

2010-2011

The above list comprises the years that strongly matched this year's set-up. There were differences of course. both last year's and 55-56 were fairly strong La Nina's; whereas this year shouldn't be as strong. As for 50- 51 that year didn't have strong blocking. I think this year will see blocking more like last years, though not quite as strong.


Storm Tracks:

These will be the dominant storm tracks for the winter of 2011-2012

These storms tracking to the west would lead to rain, mix, and ice and slop storms along the coast. Places inland would see more in the way of snow. what you saw would depend on the exact setup and location of where you live. I expect a fair share of these this winter.

The red tracks are the coastals and the purple tracks are clippers.

The blue line shows the average axis of the trough for 2011-2012
The purple lines show how the jet will set-up the main storm track

Here is the temperature outlook for the United States for the winter of 2011-2012

The Purple is well below normal
Dark blue is below normal
Lite blue  slightly below normal
Orange is normal
Yellow is above normal
Red is well above normal

Above is the Northeast snowfall outlook for 2011-2012

Purple well above average
Indigo above average
Green slightly above average
Dark blue average
Lite blue below average

Summary:

Now the good stuff. What  the heck does this mean?

Now that were officially going into winter; we have to start thinking  pattern change. I think we will see a pattern change by the middle of December. for the last five or six weeks we've had above normal temperatures. (Even with the Halloween and Thanksgiving snowstorms thrown in) However, out in the western US and Canada along with Alaska its been the opposite. So, the weather out there has not been as nice and they've seen colder temps. Over the last month and a half, the AO and NAO as be positive to neutral. The result our relatively nice weather. Well all of this is about to change, starting next week we will see the pattern began to change. By Hanukkah we will be in a much colder pattern. This will be especially true for the Great Lakes.

What do I think:

As I've outlined above, Storms will enter the Pacific Northwest move into the Plains and Midwest then head into the Northeast. It will be difficult to get a lot of Nor' Easters this year; the pattern doesn't support them as much as it did last year. For the snow lovers, the Halloween Nor' Easter is not a sign of things to come. But, that doesn't mean there won't be some. The pattern will have the storms phasing more west than we saw last year. this is why I feel 2011-2012 will be a snowy winter for the Great Lakes. But those in eastern NYS and New England shouldn't laugh. Because we will see quite a few Clippers these will make the northeast quite cold for the winter of 2011-2012.  

What to expect from the winter of 2011-2012 across the U.S.

The West:
Because of the way the storm track will setup. The Pacific northwest looks to see normal to above normal precipitation. whereas California and the Southeast will see normal precipitation.

The states in the Rockies:

If you like snow skiing Stay in the Northeast, The ridge that will develop over them, which will keep  places like Aspen Colorado from seeing as much snow as normal.

The Northern Plains:
Like last year, the northern Plains will see an extremely cold winter. I’m expecting yet another very cold winter for the Northern Plains Because I think there will be a higher than average number of Alberta Clipper's this year they should see as much snow as last year.

The Southern Plains:
They will see quite a few ice storms this winter. Parts of Texas could also see more severe weather outbreaks than normal.

The Mid West and Ohio Valley:
The storm track for the most part will be to the south and southeast. So they will see a cold and snowy winter.  

The Southeast and Gulf Coast:
If you like the sun, this will be the place to be. So they will be warmer than average. However, this could come with a price. they run the risk for more severe weather than normal.

The Northeast:

The pattern looks to be classic for a cold and snowy 2011-2012 winter. With the PDO,  AO, and the NAO being negative. we will see a deeper and more easterly jet this year. this will lead to a higher than average number of cold spells. There will be quite a few lake cutters. Also, with the larger than average number of Clippers and the greater threat of Miller B's, will keep the Great Lakes busy.  Because of the warm summer and warm fall the Lakes are very warm this year. So lake effect snows will be above normal to well above normal this winter.  Much of the Northeast will be affected by the same storm systems. Most of NYS and New England will see more snow than avearge. The exception being extreme southeast NYS and areas closer to the coast. This is because  most of the storms will track more to the west this winter. So places like the  Philadelphia and New York City metropolitan areas will see less snow and more of a mix or sloppy mess. I don't think we will see an early spring.  Traditionally, La Nina years see a cold and snowy March and first part of April.

Here is my call for snowfall amounts for some places in the Northeast.

The Tughill east of Lake Ontario will see 200-425 inches of snow this year.

Syracuse looks to see  170-180 inches.

Boston Massachusetts 46-50 inches.

Along the Mohawk Valley  100-130 inches (The higher amounts Just to the south and east of Utica.)

Albany 75-85 inches.

New York City right around 26 inches.

Buffalo 125-135 inches


Here is a link you can also checkout.

NOAA 2011-2012 winter outlook.

Well that's about it......remember this is an outlook not an forecast. I tried to be as accurate as I could. But when all is said and done, an outlook is no more than a educated  guess. I looking forward to seeing how right I am. However, we will have to wait until next spring to see.

Rebecca