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8th Annual Winter Forecast 2012-2013
It’s that time of year again for my annual winter forecast for the Southeast. Over the past 8 years I have had my ups and downs in my winter forecasting. Seasonal forecasting is very difficult and I learned a valuable lesson in that last year with a horrible miss. The combination of a strong La Nina and positive NAO all winter gave us one of the warmest winters in years across the Carolinas. That miss last year put by record at 5-3 in my winter forecasts.
This year is proving to be just a tough as EL Nino is fading and the amount of warming over parts of the artic due to sea ice loss is added to the difficulty in this years forecast. So lets start with a few of the parameters I’m looking at.
El Nino/ La Nina or ENSO(EL Nino Southern Oscillation)
The ENSO gets the most attention but it’s the end all be all of winter forecasting. As we learned in past winters the combination of other smaller oscillations can more than over comes any impacts of the ENSO. This year we were on schedule to have an EL Nino but it’s fading and I’m counting on e Neutral phase or La Nada. Here’s what the 3 phases of ENSO due to the Jetstream or storm track for the U.S.
El Nino La Nina Weak El Nino- La Nada
The weak El Nino to La Nada phase usually means slightly less precipitation and slightly milder temperatures for the South East. Here’s a typical look at the impacts on the Winter from ENSO.
The Neutral phase of the ENSO to me is the most plausible phase this winter. In fact all the climate forecast are now leaning that way. Belo forecast now has a 52% of La Nada versus a 48% chance of El Nino this winter.
For Charlotte the impacts of ENSO phase are pretty clear to see in the snowfall totals in winters where we have EL Nino or Neutral phase we tend to get more snow than than in La Nina winters. I should not last year was a La Nina Winter.
The water temperatures in the northern Pacific are running cooler while water in the western north Atlantic are warmer than average. This could help create an active east coast storm track where storm would interact with that warm water off the east coast for many Nor’easters. The warming in the Arctic due to melting sea ice this summer & which is recovering quickly could still help lead to blocking further east over Greenland. This is always the wild card in a winter forecast and I talk about that below.
North Atlantic Oscillation NAO
This oscillation was the main cause for so much cold air in 2010-2011 but also the reason for so much warm air last winter. When this index is negative we have persistent cold weather east of the Rockies. This is due to a blocking ridge of high pressure forcing cold air down into the eastern U.S. from the Arctic. The NAO is a very good indicator of cold air for the Carolinas and east coast. Only problem is it’s only something that can be forecasted out 2-3 weeks at max. There are signs that the warming in the arctic due to sea ice loss might helps create a negative NAO this winter. Though it still remains to be seen.
The Arctic Oscillation
Much like the NAO a negative phase of this index brings much colder air for the Eastern half of the country including the Carolinas. It also is hard to forecast for the entire season is only useful 2-3 weeks out. Just like the NAO the AO would appear to be set for negative territory this winter.
Other notable climate predictors I look at include the following Arctic Oscillation(AO), Pacific-North American Pattern(PNA) and the Madden Julian Oscillation(MJO). These along with solar and lunar cycles help to determine what kind of winter we will have. Looking at these cycles and especially the ENSO phase you come up with analog forecasts. These are forecasts based on what has happened in the past. Basically what happened during the winter months in the past when we had a similar set-up in these climate predictors. Below are analogs forecast for this winter based on my thinking right now.
Forecast for this Winter
There are some models that try to forecast the winter month and so far all have had mixed resulted for the East Coast and the Carolinas. So here’s my best forecast on what will happen. This year for fun too I will forecast snow totals for 2 cities in our area. Charlotte, Hickory and Boone. These 2 cities are a good cross section of winter weather from mountains-foothills-piedmont. Here we go…..
Snow & Ice:
City by City forecasts: