Spring 2013

If you thought spring was cooler than normal for the most part, you are right. Well, the exception would be the Western US, which was warmer than normal. Just last spring, it was very warm, warmest on record. That spring felt like summer came very early. This spring felt like an extension of winter.

Here is a map of temperature anomaly comparing Spring 2012 to 2013. Spring 2012 shows abnormally warm temperatures over a large portion of the US, especially over the Lower 48. Spring 2013 shows abnormally cool temperature from Alaska, Midwest, and South. Looks like all that cold air came from the Arctic.
2012-2013SpringTemperatureCompared

Here is a precipitation and temperature map ranking map. In terms of rainfall, the Midwest saw unusually wet spring. Many areas in the Midwest had their wettest spring on record. Iowa had their wettest spring on record. Spring 2013 was quite cool, especially east of the Rocky Mountain. In fact some areas had their coolest spring on record, mainly in the South and Midwest. For them, it felt like an extended winter. So, how did Spring 2013 stack up?
Spring2013Ranks

Let’s start with America from the Division Data. It was very cool throughout America, especially east of the Rocky Mountain.

America
Spring 2013
Temperature: 50.45°F
Rainfall: 7.92

Here is the spring norms for America.
Normal Spring 1895-2013
Temperature: 51.99°F
Rainfall: 7.70

Spring was below normal and below the standard deviation of 1.35. Spring in America was much cooler than normal. Quite the opposite from last spring, which was the warmest on record. So, how cool was Spring 2013 in America? Let’s look at the ranking.

Top 20 Coolest Spring For America
1.) 1917 47.45°F
2.) 1924 48.46°F
3.) 1975 48.68°F
4.) 1920 48.77°F
5.) 1950 48.97°F
6.) 1912 48.99°F
7.) 1909 49.10°F
8.) 1983 49.16°F
9.) 1960 49.19°F
10.) 1923 49.22°F
11.) 1899 49.29°F
12.) 1965 49.36°F
13.) 1971 49.43°F
14.) 1906 49.48°F
15.) 1951 49.65°F
16.) 1907 49.66°F
17.) 1970 49.69°F
18.) 1932 49.79°F
19.) 1944 49.85°F
20.) 1947 49.89°F

Spring 2013 did not make the top 20 coolest spring as it rank 38th coolest on record for America. Still cooler than normal, especially compared from last spring. It shows how much of a difference a year makes. Last spring, America wondered what happened to spring, let alone winter. 2012 could be seen as one long summer.

Rainfall was within normal. At least it is putting a dent on the severe drought, especially in the Midwest.

So, how did the Lone Star State fair for Spring 2013.

Texas
Spring 2013
Temperature: 64.20°F
Rainfall: 5.15

Here is the spring norms for Texas.
Normal Spring 1895-2013
Temperature: 65.06°F
Rainfall: 5.15

Top 20 Coolest Spring For Texas
1.) 1931 60.13°F
2.) 1915 61.47°F
3.) 1926 61.97°F
4.) 1924/1958 62.00°F
5.) 1969 62.3°F
6.) 1983 62.43°F
7.) 1987 62.7°F
8.) 1941/1947 62.77°F
9.) 1970 62.87°F
10.) 1914 63.07°F
11.) 1968/1993 63.2°F
12.) 1997 63.23°F
13.) 1973 63.27°F
14.) 1957 63.30°F
15.) 1952/1960 63.33°F
16.) 1912 63.40°F
17.) 1913/1919 63.43°F
18.) 1903/1906 63.47°F
19.) 1932 63.50°F
20.) 1917/1980 63.63°F

Spring 2013 did not make the top 20 coolest spring for Texas. Spring 2013 was the 38th coolest spring on record for Texas. Like America, a year makes a huge difference from last spring from being very warm to a much cooler spring.

Upper Texas Coast
Spring 2013
Temperature: 67.07°F
Rainfall: 9.30

Here is the spring norms for Upper Texas Coast.
Normal Spring 1895-2013
Temperature: 69.17°F
Rainfall: 10.66

This spring had temperature that were 2.1°F below normal. That is the main highlight. The standard deviation for spring temperature is 1.6°F. It is clearly a cooler than normal spring. So, how does Spring 2013 compare to past spring in terms of temperature?

Top 20 Coolest Spring For Upper Texas Coast
1.) 1931 63.80°F
2.) 1915 65.90°F
3.) 1926 65.97°F
4.) 1983 66.13°F
5.) 1969 66.57°F
6.) 1952 66.93°F
7.) 1993 66.97°F
8.) 1924/1960 67.03°F
9.) 2013 67.07°F
10.) 1937/1970 67.13°F
11.) 1932 67.17°F
12.) 1941 67.20°F
13.) 1913 67.23°F
14.) 1914 67.30°F
15.) 1901 67.40°F
16.) 1947 67.43°F
17.) 1980 67.67°F
18.) 1903 67.73°F
19.) 1988 67.77°F
20.) 1906 67.80°F

It is the ninth coolest spring on record! Yes, you read it right. Like the rest of America, Upper Texas Coast had one of the warmest spring on record in 2012. This past spring is one of the coolest on record. Weird, isn’t it? The last time Upper Texas Coast had spring that cool was in 1993.

So, why was it cool this spring? There was upper level ridging over Greenland. It causes the jet stream to go further south than usual. This allows cold air from the Arctic to march down south. March 2013 had one of the most negative Arctic Oscillation (AO). It is on top of a negative North Atlantic Oscillation (NAO). There is also ridging off the West Coast of America. Like the ridging over Greenland, it causes the jet stream to go further south than normal and allow cold air to rush in. The areas under the ridging are warmer than normal. Basically, the cool and warm air have to go somewhere. Ridging means warmer and drier, while trough means cooler and wetter.
2013Spring500mbGeopotentialHeight_JetStream

Here is what gets interesting, of the top 20 coolest springs in Upper Texas Coast, I notice a tropical system made landfall later that year. The years with top 20 coolest springs saw a tropical cyclone make landfall are:
1915
1932
1941
1947
1960
1970
1980
1983

Some of them saw major hurricanes (Category +3) make landfall, like in 1915, 1932, 1941, and 1983. In fact, I ran a correlation between Upper Texas Coast spring temperatures and tropical cyclone landfall. Here is the result.

Tropical Storm
r = -0.03
p = 0.71

Hurricane
r = 0.10
p = 0.26

Major Hurricane
r = -0.21
p = 0.02

Total Tropical Cyclone Landfall
r = -0.05
p = 0.58

There was no correlation between spring temperature and tropical storm landfall. There is some correlation between spring temperature and hurricane landfall, when the temperature is warmer. However, the p-value is not below 0.05. Now, correlation between spring temperature and major hurricane is significant as p-value is below 0.05. The correlation is negative, which means the cooler the spring, more likely to see major hurricane make landfall.

Keep in mind that correlation does not equate with causation, but interesting to note there is. Major hurricanes rarely make landfall on Upper Texas Coast as they make landfall about every 10 years on average. The closest was Hurricane Rita in 2005, but that affected East Texas and Southwest Louisiana. However, with an active hurricane season being forecasted, it increases the probability that a tropical system including a major hurricane could make landfall anywhere. It includes the Upper Texas Coast. As I say, it only takes one to make a season very devastating. Just ask the people who were affected by Alicia, Andrew, and Sandy.

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