Issuu on Google+


2013-2014 Winter Time again for my annual Winter Weather Outlook. Last year we had a Neutral signal in the Pacific Ocean, this year we will have a similar signal. Neutral Pacific years are even more difficult than La Nina or El Nino years to forecast the coming Winter months. Here's just a small part of the items I considered this year and how I think they will play out with our winter of 2013-2014. El Nino / La Nina: When looking at the El Nino / La Nina, you must look at how strong it is, when will it peak, how fast will it fade and where in the Pacific Ocean is it strongest. This year's signal is neutral and will probably stay that way for most of the Winter. It may go closer to a weak El Nino by late Winter and early Spring. Here's a chart of the forecast of the ENSO and as you can see it is forecast to stay near Neutral. Anything within 0.5 degrees above normal or 0.5 degrees below normal is considered a Neutral signal. Table 1. Forecast SST Anomalies (deg C) in the Nino 3.4 Region


2013-2014 Winter

Pacific Decadal Oscillation ( PDO ): I'm a firm believer in the Pacific Ocean having a major impact on our winter weather. Let's face it, oceans cover about 3/4 of the earth so we must pay close attention to what certain ocean currents and sea surface temperatures are worldwide when doing long term seasonal forecasts. This oscillation as the name implies, tends to last for a decade or longer, actually around 20 - 25 years. We were in the "cool" phase of the PDO from about the middle 1940's till the late 1970's. We then went into the "warm" phase of this oscillation from the late 1970's until about 2000. Since around 2000, we have gone back into the "cool" phase and this had to be factored in when looking at the forecast. Here's a graph of the PDO trends since 1900:


2013-2014 Winter Atlantic Ocean and Gulf of Mexico temperature profiles: Depending on what the temperature profiles look like in these areas will help determine where storms may be more likely to form and where they will track. Will a high pressure be more likely to form in the southeast or will low pressure be more likely there during the winter, this can greatly impact temperatures and storm tracks for us in this area. This year it does look favorable for a “ridge� of high pressure to set up over the southeast part of the country for at least part of the Winter. In the graphic below notice lots of warm water in the Gulf of Mexico and in the Atlantic. However, there is some cooler than normal water in parts of the Gulf of Mexico and off the southeast coast. That could help promote a ridge of high pressure in those areas for part of the Winter and this would shove the storm track up over this area and would lead to periods of above normal temperatures.


2013-2014 Winter North Atlantic Oscillation ( NAO ): Just like the PDO, this also will oscillate but on a much shorter time period. The NAO is very difficult to predict much more than a couple of weeks in general and then it's not always predicted well. When the NAO goes into a negative value, we generally have colder than normal temperatures and when it's positive, we normally have warmer than normal weather. The NAO has been mainly running a little positive and then a little negative the past few months, so the question here is, will that trend continue. My feeling is that we will remain in a neutral to positive phase much of the time but there will be swings to negative and this will give us some pretty large temperature swings from cold to warm.


2013-2014 Winter Arctic Oscillation ( AO ): This works similar to the NAO and when negative, we have colder weather and positive brings warmer weather. It has been back and forth the past few months. When it and the NAO both go negative, we normally see some very cold weather. That could happen a time or two but I think we will see it more positive than negative this Winter.


2013-2014 Winter Atlantic Multidecadal Oscillation (AMO): This is based on the sea surface temperatures mainly in the northern Atlantic Ocean. It’s currently in the “warm phase”. We are still learning about the AMO but we tend to see more of a “blocking” pattern when it’s in the warm phase and this brings shots of colder weather into the eastern part of the United States during the winter months.


2013-2014 Winter Snowpack in Canada and the US: This helps to show how much modification air masses will have when coming down from the cold far northern reaches of Canada and Alaska. The snowpack here in late November is a little more than normal and there is more in the Rookies and Northern Plains states as compared to this time last year. Notice the difference in snow cover from November 2012 to this November. One thing to notice is even with more areas covered in snow in the Rookies and Plains states, the snow cover is not as heavy this year.


2013-2014 Winter


2013-2014 Winter Volcanic activity worldwide: You may say what does a volcano half way around the world have to do with our weather? That's a good and reasonable question but remember that the "weather" travels worldwide and is impacted by things many thousands of miles away ( such as La Nina way out in the Pacific Ocean ). Let me give you an example: On April 10th, 1815 there was a major eruption of the volcano Tambora in Indonesia. The year that followed ( 1816 ) is known as "the year without a summer." That summer there was frost here in the Midwest and even snow in the Great Lakes and New England and this was caused by a volcano eruption thousands of miles away. We did have a couple of notable eruptions in the last few years. One was in Iceland back in 2010 and then later in 2010 a pretty major eruption happened in Indonesia. Within the last few months we’ve had another eruption in Indonesia and Japan. I believe a volcano eruption in the southern latitudes such as in Indonesia will have a bigger impact on weather patterns than one in the more northern latitudes. Depending on the amount of ash being thrown into the atmosphere and depending on how high into the atmosphere it reached, will determine any impact on weather patterns. The impacts from those eruptions can be felt for around 3 – 5 years so this needed to be factored into the outlook. However, most of these did not get the ash high enough into the upper atmosphere to have a major impact in the forecast. Sun activity: The sun had been pretty inactive for a few years but as become much more active recently. There are still many questions on what impact we see with long term temperature predictions and solar activity but another factor looked at again this year. Here's a chart of the solar activity since 1995 and as you can see we reached a low around 2009 and we saw an increase after that but a drop in the last couple of years and it’s running lower than forecast.


2013-2014 Winter Fall trends: I look at how weather patterns in October and November from the past compare to this year and how past winters in those years turned out. Many times we find that a warm November brings a warmer than normal winter and a colder November will many times bring on a colder than normal winter. However this does not always happen as last November was colder than normal and last Winter was warmer than normal. We can sometimes get a clue to the storm tracks we will see in the Winter based on what happens in the Fall. After taking all those things into consideration along with a few others, I came up with what we call "analog years." These are years when things like El Nino, PDO, hurricane season, volcanic activity and so on are similar. I came up with the following analog years that I used: '79-’80, '80-’81, '89-'90' , '92-’93, '93-’94, '96-’97, '01-’02, ‘03-’04, '12-’13. One of those analog years was ‘89-’90 and that year produced the second coldest December on record and the all time record low for December at -22 but the Winter was very mild! It was a winter of extremes. I then give each analog year a weight value based on how close I think it is and come up with a formula to produce some numbers to be used in my winter outlook.


2013-2014 Winter Fall trends: I look at how weather patterns in October and November from the past compare to this year and how past winters in those years turned out. Many times we find that a warm November brings a warmer than normal winter and a colder November will many times bring on a colder than normal winter. However this does not always happen as last November was colder than normal and last Winter was warmer than normal. We can sometimes get a clue to the storm tracks we will see in the Winter based on what happens in the Fall.

After taking all those things into consideration along with a few others, I came up with what we call "analog years." These are years when things like El Nino, PDO, hurricane season, volcanic activity and so on are similar. I came up with the following analog years that I used: '79-’80, '80’81, '89-'90' , '92-’93, '93-’94, '96-’97, '01-’02, ‘03-’04, '12-’13. One of those analog years was ‘89-’90 and that year produced the second coldest December on record and the all time record low for December at -22 but the Winter was very mild! It was a winter of extremes. I then give each analog year a weight value based on how close I think it is and come up with a formula to produce some numbers to be used in my winter outlook.


2013-2014 Winter So after much work on it this year, here is my Winter Outlook. Walker's Winter Outlook 2013-2014 ------------------------------------------------------1. Winter of Extremes 2. Colder than last winter 3. Some cold in early December 4. December will be warmer than normal 5. First 2“+ snow not till after December 12th 6. More windy days than normal 7. Large temperature swings ( 60 degree + from high to low for the Winter ) 8. Coldest part of Winter will be the second 1/2 9. There will NOT be a white Christmas ( at least 1“ of snow on the ground Christmas morning ) 10. January Near normal temperatures 11. Three sub zero days ( none the last two years ) 12. Increased chance of a couple of ICE events this year 13. NO major ice storm 14. At least 1 record or near record high temperature 15. At least 1 record or near record low temperature 16. One or two severe t-storm outbreaks 17. February will have BELOW normal temperatures 18. Temperature will be ABOVE normal Forecast is 31.7 Normal is 31.2 19. Precipitation will be ABOVE normal Forecast is 9.00" Normal is 8.88" 20. Snowfall will be BELOW normal Forecast is 14.5“ Normal is 16.5"

Need to print just this page: CLICK HERE



Walker's Winter outlook 2013-2014