2011-2012 Winter Forecast Part 2

Let’s look at the atmospheric and ocean patterns besides El Nino/La Nina in those analog years. Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO) is by season. North Atlantic Oscillation (NAO), Arctic Oscillation (AO), Pacific-North American Teleconnection Pattern (PNA), and Quasi-Biennial Oscillation (QBO) are by month because they can change quickly since they are in the atmosphere, not ocean.

1917-1918
Winter PDO = -8 Weak Cool
Winter AMO = -17.5 Strong Cool
December NAO = -18 Strong Negative
January NAO = -45 Strong Negative
February NAO = +25 Strong Positive
Overall Winter NAO = -12.7 Moderate Negative
December AO = N/A
January AO = N/A
February AO = N/A
Overall Winter AO = N/A
December PNA = N/A
January PNA = N/A
February PNA = N/A
Overall Winter PNA = N/A
December QBO = N/A
January QBO = N/A
February QBO = N/A
Overall Winter QBO = N/A

There is no data for AO, PNA, and QBO, since earliest goes back to the late 1940s or 1950s.

1956-1957
Winter PDO = -12.6 Moderate Cool
Winter AMO = -3.9 Neutral
December NAO = +17 Strong Positive
January NAO = +18 Strong Positive
February NAO = -10 Moderate Negative
Overall Winter NAO = +8.3 Weak Positive
December AO = +0.01 Neutral
January AO = +20.6 Strong Positive
February AO = -15.1 Strong Negative
Overall Winter AO = +1.8 Neutral
December PNA = -3.1 Neutral
January PNA = -11.9 Moderate Negative
February PNA = -11.9 Moderate Negative
Overall Winter PNA = -9.0 Weak Negative
December QBO = -15.02 Easterly
January QBO = -13.05 Easterly
February QBO = -11.89 Easterly
Overall Winter QBO = -13.32 Easterly

2000-2001
Winter PDO = +4.7 Neutral
Winter AMO = -5.5 Weak Cool
December NAO = -22 Strong Negative
January NAO = -1 Neutral
February NAO = -5 Weak Negative
Overall Winter NAO = -9.3 Moderate Negative
December AO = -23.5 Strong Negative
January AO = -9.6 Moderate Negative
February AO = -6.2 Weak Negative
Overall Winter AO = -13.1 Moderate Negative
December PNA = +12.3 Moderate Positive
January PNA = +15.1 Strong Positive
February PNA = -1.6 Neutral
Overall Winter PNA = +8.6 Weak Positive
December QBO = -14.6 Easterly
January QBO = -15.7 Easterly
February QBO = -15.5 Easterly
Overall Winter QBO = Strong Easterly

2008-2009
Winter PDO = -12.7 Moderate Cool
Winter AMO = -2.8 Neutral
December NAO = +3 Neutral
January NAO = +15 Strong Positive
February NAO = -3 Neutral
Overall Winter NAO = +5 Weak Positive
December AO = +6.5 Weak Positive
January AO = +8 Weak Positive
February AO = -6.7 Weak Negative
Overall Winter AO = +2.6 Neutral
December PNA = -14.1 Moderate Negative
January PNA = +6.1 Weak Positive
February PNA = -9.5 Weak Negative
Overall Winter PNA = -5.8 Weak Negative
December QBO = +10.5 Westerly
January QBO = +10.7 Westerly
February QBO = +12.3 Westerly
Overall Winter QBO = +11.2 Westerly

Here is the correlation of ocean and atmospheric patterns on regions in America. They are based on seasonal average anomalies from December to February.


PDO
Of the four analog winters, three were in cool phases. The only winter in a neutral or warm phase was 2000-2001. Pacific can be cooler due to season variables and ENSO . A cooler PDO is more likely to have warmer and drier winters on average. It is opposite when the PDO is a warmer phase. Currently, we are in a cool cycle of PDO. Cool phase of PDO is more likely to see La Nina than El Nino since the water is cooler. The opposite happens when PDO is in a warm phase, when we see more El Nino. PDO impact on temperature and rainfall is similar to El Nino for Texas. Cooler the PDO, the drier and warmer it is. Warmer the PDO, the wetter and cooler it is.


AMO
Two of the four winters were in neutral phase. Two of the winters were in cool phase. Three of the four winters were in the warm phase of Atlantic, which is during the “active” or warm cycle of the Atlantic Hurricane Season. 1956-1957 was during the warm phase from 1926 to 1971, while 2000-2001 and 2008-2009 was during the current warm phase of the Atlantic. The Atlantic can be cooler due to seasonal variation and AO and NAO. 1917-1918 was during the cooler and less active period of the Atlantic, which was from 1900-1925. Currently, we are in the warm cycle of AMO. AMO does not have much of an impact on Texas.


NAO
Two of the four winters had overall negative NAO (1917-1918 and 2000-2001). The winters were quite cold, especially in January of 1918. The Northeast and New England had their coldest winter on record in 1917-1918. The 1917-1918 winter is yet to be beaten even to this very day. December 2000 was cold throughout the nation, especially east of the Rocky Mountains. Houston had its third coolest December on record, only 1983 and 1989 were cooler. A negative NAO leads to cooler winters.

Two of the four winters had positive NAO (1956-1957 and 2008-2009). The winter of 1956-1957 was quite warm, especially in the South and East Coast. 2008-2009 is interesting in that the South was warmer than normal. Up North, it was cooler than normal. A positive NAO leads to warmer winters.


AO
The AO can change quickly within weeks to months. It can go neutral than positive than negative in weeks. The winter of 1956-1957 went from neutral, positive, than negative. The AO stayed largely negative in winter of 2000-2001. AO in 2008-2009 went from positive than negative. A negative AO allows cold air to travel further south than normal leading to freezes, while positive AO generally has a blocking pattern that inhibits cold air to travel southwards. The more negative AO is, the cooler the winters will be, especially east of the Rocky Mountains. A negative AO has been responsible for Arctic blasts in the past.


PNA
There is no PNA data from 1917-1918. Two of the three winters (1956-1957 and 2008-2009) had an overall negative PNA. Only one winter (2000-2001) had a positive PNA. A positive PNA means cooler temperatures and more rain for Texas. A negative PNA likely means cooler temperatures for the Western United States.


QBO
There is no QBO data from 1917-1918. In two of three winters, the QBO was negative or easterly. Only one winter was a positive or westerly QBO (2008-2009). QBO likely has relationship with temperature. On the other hand, there is a relationship with QBO and rain. The more negative or easterly QBO is, the wetter winter is for Texas and the South. A positive or westerly QBO is wetter for the West. Interestingly, for the West, a easterly QBO means cooler, but the correlation is not as strong. It is unclear what impact QBO has on temperature. We do know that QBO happens in the stratosphere and when the stratosphere warms up, it is signs that we may see a freeze, since the energy is being distributed somewhere else.

All the images are from US Climate Division Dataset Seasonal Correlation Page

Conditions for December 2011
ENSO
Moderate La Nina

PDO
Cool Phase

AMO
Cool Phase

NAO
Positive

AO
Positive

PNA
Positive

QBO
Easterly

Data for ENSO is from ENSO Cycle: Recent Evolution, Current Status and Predictions. Data for PDO, NAO, AO, and PNA are from Daily Indices during last 120 days in Ascii format using GDAS. Data for AMO and QBO are from Climate Indices: Monthly Atmospheric and Ocean Time Series

What do I think this upcoming winter will be like? I think we could see multiple cold blasts and winter storms, especially up north. It is going to be dependent on NAO and AO because it can change month to month. If NAO goes negative, we could see more cold blasts in America and Texas. If NAO goes positive, there is likely a period of warmth in the winter. Also, PNA is an important factor as well and changes month to month like NAO and AO. A positive PNA means cooler winter as well. QBO has little impact on temperature, but it could have an impact on rainfall. If the QBO is still  easterly by February, we could see more rain.

La Nina winters are warmer in generally because it is drier. The lack of moisture does not moderate the temperature. This upcoming winter should be a roller coaster ride like last winter. In regards to rainfall, I think we could have periods of rain and than periods of dryness. However, we should prepare if the drought worsens this winter. Let us hope the drought ends in 2012. I think this winter will be average to slightly above average in temperature department. In regards to rainfall, I think the rainfall should be within average or below, which is typical of La Nina.

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