2011-2012 Winter Forecast Part 1

Old Man Winter is back and it is time to celebrate Christmas and New Years. Fall was a huge gap between warm and cool and dry and wet. This past summer was the hottest on record for Texas and hottest ever going back to 1895. America endure its hottest summer since 1936. 1936 was very hot, especially in the Midwest during the Dust Bowl. The 1930s saw some of the worst droughts on record and it occurred during the Great Depression. It is no surprise that droughts contribute to a weakened economy. The current recession started in late 2007 to early 2008, which also marked the start of the drought.

The Texas drought is the worst since 1789, 1918, and 1956. The 1789 drought was based on tree rings. Now, we have to wonder what this winter will be like. We can look at the past and forecast what 2011-2012 winter will be like for America and Texas. The analog years I choose for 2011-2012 winter are 1917-1918, 1956-1957, 2000-2001, and 2008-2009. The reason they were chose were that the winters occurred with a second La Nina. Also, the La Nina in those analog years were weaker as this one should be forecasted to be a weak one.

What does this mean? We should have a drier and warmer than normal winter. However, cold blasts have occurred in La Nina winters. The winter of 2010-2011 was a La Nina winter and there were multiple cold blasts, especially in February 2011. December 2000 was colder than normal due to the Arctic Oscillation moving south. It shows that La Nina/El Nino is not the only factor. This article will be a 2 part, first on El Nino and analog statistics. The second part will be other atmospheric and ocean patterns besides La Nina.

Here is what rainfall and temperature would look like for America during those analog winters.

Analog Year Climate
USA
Rainfall Mean = 5.63
Rainfall Median = 5.68
Standard Deviation = 0.22
Driest = 5.33 (1917-1918)
Wettest = 5.84 (1956-1957)
Temperature Mean = 32.4°F
Temperature Median = 32.7°F
Standard Deviation = 2.0
Coolest = 34.5°F (1956-1957)
Warmest = 29.9°F (1917-1918)

Texas
Rainfall Mean = 3.58
Rainfall Median = 3.19
Standard Deviation = 2.28
Driest = 1.56 (2008-2009)
Wettest = 6.38 (2000-2001)
Temperature Mean = 48.5°F
Temperature Median = 48.3°F
Standard Deviation = 3.1
Coolest = 51.7°F (1956-1957)
Warmest = 45.6°F (1917-1918)

Upper Texas Coast
Rainfall Mean = 6.38
Rainfall Median = 6.84
Standard Deviation = 2.80
Driest = 2.84 (2008-2009)
Wettest = 8.21 (2000-2001)
Temperature Mean = 56.1°F
Temperature Median = 55.4°F
Standard Deviation = 3.2°F
Coolest = 53.4°F (1917-1918)
Warmest = 60.1°F (1956-1957)

Here is the 500 millibar Geopotential Height in those analog years.

There is ridging at 30,000 feet south of Alaska and another one over the Southern US.

Here is the average rainfall and temperature weak La Nina winter from 1895 to 2011. The overall mean for winter is from 1895 to 2011. Let’s start with rainfall.
USA
Weak La Nina
Mean = 6.13
Median = 6.12
Standard Deviation = 0.57
Driest = 5.16 (1903-1904)
Wettest = 7.26 (1908-1909)

Overall Winter
Mean = 6.43
Median = 6.39
Standard Deviation = 0.88
Driest = 4.08 (1976-1977)
Wettest = 8.68 (1997-1998)

Weak La Nina for America as a whole does not have a huge difference on rainfall. The northern part of America is wetter, while the southern part is drier during a La Nina. The jet stream is further north during a La Nina. Some areas this winter could see droughts worsen, especially in the South. Interesting to note that the driest winter occurred in 1976-1977, which was an El Nino. The West Coast was experiencing a drought at the time. It comes to show that not all La Nina and El Nino are the same.

Texas
Weak La Nina
Mean = 4.35
Median = 4.26
Standard Deviation = 1.99
Driest = 1.56 (2008-2009)
Wettest = 7.41 (1944-1945)

Overall Winter
Mean = 5.08
Median = 4.93
Standard Deviation = 1.90
Driest = 1.56 (2008-2009)
Wettest = 13.23 (1991-1992)

Weak La Nina for Texas is not much drier in terms of rainfall. The winter rainfall total is wide. It can either bone dry or abnormally wet. So, there is some hope that this winter may not be as dry. However, we should still assume that this winter will be drier than normal. The wettest winter on record occurred in an El Nino. It was wet because of the December 1991 Flood or Christmas Day Flood, which happened over a large area of Texas. It resulted in massive flooding.

Upper Texas Coast
Weak La Nina
Mean = 8.83
Median = 8.36
Standard Deviation = 3.49
Driest = 2.84 (2008-2009)
Wettest = 17.56 (1933-1934)

Overall Winter
Mean = 10.68
Median = 10.17
Standard Deviation = 3.46
Driest = 2.84 (2008-2009)
Wettest = 23.72 (1991-1992)

Weak La Nina for Upper Texas Coast is drier, but not abnormally dry. Some Weak La Nina winters were quite wet. So, there is a possibility that we could have a wetter than normal winter. That would be a good thing with the ongoing severe drought. Again, the wettest winter occurred in 1991-1992. It was quite a wet winter from what I remember. The early 1990s was quite wet, it was a wet spell, opposite of a drought. I am nostalgic for a wet spell.

Now, let’s look at temperature.
USA
Weak La Nina
Mean = 32.9°F
Median = 33°F
Standard Deviation = 1.6
Coolest = 29.9°F (1917-1918)
Warmest = 36.1°F (2005-2006)

Overall Winter
Mean = 33°F
Median = 33.2°F
Standard Deviation = 2
Coolest = 27.3°F (1978-1979)
Warmest = 37.2°F (1999-2000)

America during a Weak La Nina is generally not abnormally warm or cold on average as a whole. It is more regional. The northern region is cooler and wetter in a La Nina winter since the jet stream is further north. The southern region is warmer and drier because the jet stream is further north, which transports storms systems from the west.

Texas
Weak La Nina
Mean = 48.8°F
Median = 48.5°F
Standard Deviation = 2.1
Coolest = 45.5°F (1967-1968)
Warmest = 52.4°F (1910-1911)

Overall Winter
Mean = 48°F
Median = 47.9°F
Standard Deviation = 2.3
Coolest = 42.5°F (1894-1895/1898-1899)
Warmest = 53.1°F (1906-1907)

Weak La Nina winter for Texas is generally a normal winter in terms of temperature. However, winters can get warm during a Weak La Nina.

Upper Texas Coast
Weak La Nina
Mean = 56.2°F
Median = 56.3°F
Standard Deviation = 2.2
Coolest = 52.5°F (1967-1968)
Warmest = 60.5°F (1910-1911)

Overall Winter
Mean = 55.1°F
Median = 55.2°F
Standard Deviation = 2.6
Coolest = 48.9°F (1977-1978)
Warmest = 60.9°F (1950)

Upper Texas Coast winter temperature is warmer than normal, but not abnormal. There are winters that are cooler than normal, like in 2000-2001.

Here is the climate in the analog years I mentioned for Winter 2011-2012.

1917-1918
USA
Rainfall Total = 5.33
Temperature Average = 29.9°F

The rainfall in the winter of 1917-1918 is below the standard deviation of a typical winter for America, 0.55 or less. Anything within the standard deviation, plus or minus, is considered normal. Anything pas the standard deviation is considered unusual. It was an abnormally dry winter for America due to the severe drought that plagued Texas and Southern plains in 1917.

It was also abnormally cold in winter of 1917-1918. The air is also drier as there is less rain, which means colder air since lack of moisture. Moisture moderates air temperature, which is why coastal areas do not get too hot or cold.

Texas
Rainfall Total = 1.89
Temperature Average = 45.6°F

No surprise in Texas, which was in the center of the Great Drought of 1917-1918.

Winter in Texas was abnormally cold, 0.1 degree cooler from the standard deviation of 2.3. Not surprising it was cooler due to a dry winter.

Upper Texas Coast
Rainfall Total = 5.46
Temperature Average = 53.4°F

It also really dry in the Upper Texas Coast. Houston had its driest year on record in 1917.

Winter temperature was within the average in 1917-1918. It is within the standard deviation of 2.6.

1956-1957
USA
Rainfall Total = 5.84
Temperature Average = 34.5°F

America’s winter rainfall total is within average. Not too dry even thought the Southern Plains again that time was in grips of the Great Drought of 1950s. Again, that was centered in Texas.

Winter in 1956-1957 was above average, but not unusually warm.

Texas
Rainfall Total = 4.48
Temperature Average = 51.7°F

The rainfall total is within average. Texas was seeing improvement from the Great Drought of 1950s as rain was returning. 1956 is one of the driest years on record in Texas going back to 1895. Texas was in grips of a severe drought that would not be seen again until late 2010.

Texas was abnormally warm in the winter of 1956-1957.

Upper Texas Coast
Rainfall Total = 9.00
Temperature Average = 60.1°F

The Upper Texas Coast had a normal winter in terms of rainfall. It must have been a welcoming sight as they had one of the driest years on record.

The Upper Texas Coast had a unusually warm winter. I am pretty sure most people were not complaining at the time since it was raining, which was gradually ending the Great Drought.

2000-2001
USA
Rainfall Total = 5.60
Temperature Average = 31.7°F

Rainfall was not unusual in the winter of 2000-2001.

The winter of 2000-2001 was below average, but not abnormally cold. December of 2000 was quite cold for America due to the polar vortex moving southwards.

Texas
Rainfall Total = 6.38
Temperature Average = 46.1°F

Texas saw normal rainfall total in the winter of 2000-2001. That is considered welcoming considering that they had a severe drought of 1999-2000.

Texas had below normal temperature in the winter. December 2000 was quite cold as the rest of America east of the Rocky Mountains was cold too.

Upper Texas Coast
Rainfall Total = 8.21
Temperature Average = 53.5°F

The Upper Texas Coast had normal rainfall total. I remember that winter being rainy, often in the form of light rain. That was a good thing as it was a dry 2000.

2000-2001 Winter was also cold in the Upper Texas Coast. I remember that winter being cooler than normal. A reprieve from the hot summer we had in 2000.

2008-2009
USA
Rainfall Total = 5.75
Temperature Average = 33.6°F

America was not abnormally dry in the rainfall department.

Winter temperature for America was within average. It was cooler than normal up north.

Texas
Rainfall Total = 1.56
Temperature Average = 50.4°F

Texas had its driest winter on record in the winter of 2008-2009. The Drought of 2008-2009 gripped Texas and was spreading.

Texas had a warm winter from the lack of rain. As mentioned, drier weather means warmer weather because there is a lack moisture to moderate the air temperature. Also, the cold air was mostly to the north.

Upper Texas Coast
Rainfall Total = 2.84
Temperature Average = 57.3°F

The year Hurricane Ike ravaged the Upper Texas Coast and the December 10, 2008 snow. The Upper Texas Coast had its driest winter on record. It helped set the stage for the Drought of 2008-2009 that gripped Texas.

In the temperature department, it was within average. I remember that winter being rather warm. It shows that snow can happen in La Nina winters.

The second part will be an analysis on the analog years and other atmospheric and ocean patterns.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s