2012-2013 Winter Forecast

TrainSnow

The world did not end on winter solstice as the Mayan Calendar ends and starts a new one. Tragically, 27 lives, including 20 children were cut too short on December 14, 2012 at Sandy Hook Elementary School. Winter is upon us again, which means it is time to think about Christmas. It is Christmas time and get ready to be merry. Get your stockings and Christmas tree ready for Santa Claus. What kind of gift will Santa give us for winter? Will it be a cold or warm winter or wet or dry winter? Well, let’s look at what this winter will be like.

2012-2013WinterAnalog500mbGeopotentialHeight

Geopotential height for winter analogs.

This winter forecast has proved challenging as I mainly use El Nino to determine what kind of winter we could see. El Nino is pretty much gone due to Pacific Decadal Oscillation (PDO) being very cold. The Atlantic Multidecadal Oscillation (AMO) is also a factor in the winter forecast. This complicates things. To make matters worse, the North Atlantic Oscillation (NAO), Arctic Oscillation (AO), Pacific North America (PNA), East Pacific Oscillation (EPO)/North Pacific Index (NP), and Quasi-Biennial Oscillation (QBO) can change quickly as they are atmospheric, not in the ocean. The analogs I would use for this winter are:
1951-1952
1963-1964
1976-1977
1989-1990
1996-1997
2001-2002
2006-2007

I chose them based on the fact we had a La Nina winter previously and are heading into either Neutral to weak El Nino. This makes the winter forecast more complicated than ever with El Nino gone for the time being. Most forecast models have Neutral to next summer. However, I still cannot rule completely rule out a weak El Nino this winter. What is complicating things in regards to to El Nino is PDO, which is in a cool phase. PDO occurs in the Northeast Pacific. The unusually cool PDO is suppressing any El Nino formation on top of the trade winds. There is a correlation between PDO and El Nino. Warm PDO means more chance for El Nino, while cool PDO means more chance for La Nina.

PDO is a major factor. As mentioned, PDO is in a cool phase. When PDO is in a cool phase, the Southern half of the US including Texas is drier because the jet stream is further north due to less temperature gradient. The 1950s and the current drought occurred in a cool PDO. A warm PDO means wetter weather for the Southern US and Texas. The early 1990s was in a warm phase of PDO, which explains why it was so rainy that time in Southeast Texas. On the other hand, a warm PDO means increased risk for drought for Northern US. The 1930s drought, also known as the “Dust Bowl”, occurred in a warm PDO, which meant the jet stream went further south carrying storms away from the Midwest. It was on top of a warm Atlantic Multidecadal Oscillation (AMO). The early 1990s was in a cool AMO phase.

So, how were these analog years like in terms of temperature and precipitation? In terms of temperature, it should be cooler than normal in the southern part of the US. Area up north should be warmer than normal. In terms of precipitation, it should be wetter in the South, while areas out West could have a drier than normal winter, which could prolong the drought.

Could this winter see cold blasts that affect most of America? The answer is yes, especially with the NAO/AO trending towards negative. If the NAO/AO is deep in negative territory, 2 standard deviations below, cold air will travel south regardless of El Nino or not. However, not all freezes occur with a negative NAO. We should also look at EPO as well. The December 1983 and February 1989 freeze occurred with a positive EPO, positive NAO, and negative PNA.

Some of these analogs had winter blasts like in the winter of 1976-1977, 1989-1990, and 1996-1997. The winter of 1976-1977 is one of the coldest winters on record for America. December 1989 had a huge Arctic blast where many record lows were set. The 1989 freeze is on par with December 1983, February 1895, and the king of all freezes, February 1899. Will Southeast Texas see snow or ice this coming winter? The answer is possibly as some of the analog winters have seen snow and ice storms. Here are the analog winters that saw snow or ice:

Snow
February 21, 1964
December 22, 1989

Ice
November 28-29, 1976
January 2, 1977
January 12-14, 1997
January 16-17, 2007

Those analog winters saw more ice storm than snow. Ice storms are more dangerous than snow as they cover the road with ice which makes them dangerous to drive on. It is interesting to note that there was an ice storm in late November of 1976. It is the earliest ice storm on record for Houston area.

Another factor that deserves looking into is QBO. It occurs in the stratosphere, which are equatorial zonal wind flow.

Winter Analog Climate Pattern (Based on December to February average)
1951-1952
ENSO-Weak El Nino
PDO-Cool Phase
NAO-Positive
AO-Positive
PNA-Negative
EPO/NP-Negative
QBO-Negative (Easterlies)

1963-1964
ENSO-Weak El Nino
PDO-Cool Phase
NAO-Negative
AO-Negative
PNA-Positive
EPO/NP-Negative
QBO-Positive (Westerlies)

1976-1977
ENSO-Weak El Nino
PDO-Warm Phase
NAO-Negative
AO-Negative
PNA-Positive
EPO/NP-Positive
QBO-Negative (Easterlies)

1989-1990
ENSO-Neutral
PDO-Warm Phase
NAO-Positive
AO-Positive
PNA-Negative
EPO/NP-Negative
QBO-Negative (Easterlies)

1996-1997
ENSO-Neutral
PDO-Warm Phase
NAO-Negative
AO-Negative
PNA-Negative
EPO/NP-Positive
QBO-Negative (Easterlies)

2001-2002
ENSO-Neutral
PDO-Cool Phase
NAO-Positive
AO-Positive
PNA-Positive
EPO/NP-Negative
QBO-Positive (Westerlies)

2006-2007
ENSO-Weak El Nino
PDO-Warm Phase
NAO-Positive
AO-Positive
PNA-Positive
EPO/NP-Negative
QBO-Positive (Westerlies)

2012-2013WinterAnalogsClimate

Winter divisional climate.

Based on the overall pattern, especially with ENSO and PDO, I think this season is most likely going to resemble winter 1951-1952, 1963-1964, and 2001-2002. The reason is that ENSO is either Neutral or weak El Nino and are in a cool PDO phase. As for NAO, AO, PNA, and EPO, they change constantly since they occur in the atmosphere. They too play a role and can give cold winters regardless of ENSO and PDO. A negative NAO and AO can produce Arctic blasts regardless of ENSO and PDO. Some big Arctic blasts have occurred in La Nina or Neutral due to a negative NAO and AO, like in February 1895, January/February 1951, January and February 1985, and February 2011. However, freezes have occurred when NAO and AO were positive, like in December 1983 and February 1989 where the EPO was positive. What does it tell you? Freezes will happen regardless of ENSO and PDO.

2012-2013WinterAnalogWeather

Analog winter weather climate for North America.

Rainfall
Most areas will likely see equal chance for above or below normal rainfall. The map shows that in those analog years, most areas had rainfall within average, with the exception of the West Coast, where they had below rainfall. It is regardless of PDO. However, QBO is in a westerly phase and trending easterly (positive). This could mean some areas may see less rainfall. We shall see how QBO behaves this winter. It would be nice if America saw a wet winter as there is a severe drought going on.

Temperature
The analog years had temperatures that was not abnormally cold or warm. Again, there is an equal chance for cold or warm winter. The cooler temperatures are mostly in the Rocky Mountain region of America. The warm temperatures are east of the Mississippi, especially with a cool PDO. Overall, I think winter will be within average or warmer, not unusually warm like last winter. However, I think there are good chances we could see Arctic blasts especially with NAO and AO trending negative.

I use analog years to get a good idea what the season will be like. I like to look at the past, which I can use to predict the future. Everything has a pattern as nothing is really that random.

I would like to extend my deepest and utmost condolences to the families who lost loved ones in the Sandy Hook Massacre. I wish everyone a Merry Christmas.

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