Drought Misery Index

With the ongoing drought, I came up with the Drought Misery Index (DMI), which is similar to the Misery Index for the economy. Here is the formula for Drought Misery Index.

Palmer Drought Severity Index (PDSI) + Precipitation (PCP) = Drought Misery Index

Example:
-8.00 + 1 = -7.00

The more negative the DMI, the worse the drought is. Here is the current DMI, based on September outcome.

America
-2.78
-4.78 (PDSI) + 2.00 (PCP)
Lowest: -6.01 August 1934
Highest: +9.91 May 1983

Texas
-2.49
-3.78 (PDSI) + 1.29 (PCP)
Lowest: -7.22 September 1956
Highest: +15.51 October 1919

Upper Texas Coast
0.38
-2.05 (PDSI) + 2.43 (PCP)
Lowest: -4.64 July 1925
Highest: +20.98 October 1949

All data is from the Division Data and it can change as more data is put in and averaged out.

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2011 Hurricane Season So Far and Stats

We are now in October of the 2011 Atlantic Hurricane Season. So far we have 16 storms, 4 hurricanes, and 3 major hurricanes with an Accumulated Cyclone Energy (ACE) of 99. So, how is this season stacking up to be? Is it truly an active season? All statistical values are from 1870 to 2010.

16 Storms
Mean = 9
Std Dev = 4.02
Kurtosis = 2.88
S.E. Kurt = 0.41
Skewness = 1.14

We are way above average in number of storms. Anything above a standard deviation of 4 is extremely active.

4 Hurricanes
Mean = 5
Std Dev = 2.61
Kurtosis = 0.75
S.E. Kurt = 0.41
Skewness = 0.80

We are close to average in number of hurricanes. It is within average. Anything +/-3 is above or below average is unusually active or inactive.

3 Major Hurricanes
Mean = 2
Std Dev = 1.75
Kurtosis = 0.84
S.E. Kurt = 0.41
Skewness = 1.10

We have an average number of major hurricanes so far this season. Anything above standard deviation of 2 is active, which would be 4 or more major hurricanes.

ACE of 99
Mean = 91
Std Dev = 54.28
Kurtosis = 0.40
S.E. Kurt = 0.41
Skewness = 0.93

We are withing average of ACE for the 2011 season. Anything above standard deviation of 54 is hyperactive, which would be 145.

ACE/Storm of 6.2
Mean = 9.78
Std Dev = 4.22
Kurtosis = -0.18
S.E. Kurt = 0.41
Skewness = 0.58

The ACE/Storm is rather low, but within the average. Below average ACE/Storm would be below standard deviation of 4.22 or 5.56 or less ACE/Storm.

25% Became Hurricanes
Mean = 0.59 (59%)
Std Dev = 0.17
Kurtosis = 0.89
S.E. Kurt = 0.41
Skewness = -0.29

The percentage of storms that became hurricanes in the 2011 season is unusually low, at 25 percent. In a normal season, 59 percent of storms become hurricanes. Even if we subtract the standard deviation of 0.17 from the mean, it is 0.42 or 42 percent.

18.8% Became Major Hurricanes
Mean = 0.21 (21%)
Std Dev = 0.15
Kurtosis = -0.02
S.E. Kurt = 0.41
Skewness = 0.56

The percentage of major hurricanes is within average. An Atlantic season with 6 percent or less would be an outlier. The last season with such a low percentage was 1994. No major hurricanes formed in 1994 as it was a quiet year due to El Nino.

The last time we had a season with many storms in a short time was 2005, which is the most active season record. 2005 had 28 storms, 15 hurricanes, and 7 major hurricanes with an ACE of 248. 2005 is an outlier, except some things and I will show you that.

28 Storms
Outlier

15 Hurricanes
Outlier

7 Major Hurricanes
Outlier

ACE of 248
Outlier

ACE/Storm of 8.9
The ACE/Storm in 2005 is within the mean. The reason is many of those storms in 2005 formed close to land. The ACE/Storm of 2004 was 14.9 because only 15 storms formed that year and many formed in the open Atlantic, intense, and were long lived.

53.6% Became Hurricanes
The percentage of storms that became hurricanes in 2005 is also within in the mean. 15 hurricanes is an outlier in that regard, but when it comes to percentage, not so. Keep in mind that 28 storms formed in 2005 and that right there is an outlier.

18.8% Became Major Hurricanes
The percentage of storms becoming major hurricanes is also within the mean. 1999 had 12 storms and 5 became major hurricanes, which is 41 percent, which makes it more than 0.15 (15 percent) standard deviation above the mean.

Source of data.
NOAA HRD-How many tropical cyclones have there been each year in the Atlantic basin? What years were the greatest and fewest seen?

Spring 2011

If you thought spring was really warm and dry. You are right, it was warm and dry. Here is the outcome for Spring, which is from March to May for the Upper Texas Coast.

Temperature
71.8°F

1895-2011 Spring Temperature
Mean
69.2°F

Median
69.1°F

Standard Deviation
1.6

Percentile
5th
67°F

25th
68.2°F

50th
69.1°F

75th
70.5°F

95th
71.5°F

Spring 2001 temperature is 2.6°F above normal, which is abnormally warm. Spring 2011 is the fifth warmest spring on record, going back to 1895. Here is where Spring 2011 temperature ranks.
1.) 1908 72.3667°F
2.) 1967 72.2000°F
3.) 1963 72.1667°F
4.) 2006 72.0333°F
5.) 2011 71.8000°F
6.) 1929 71.7000°F
7.) 1953 71.4333°F
8.) 1991 71.4333°F
9.) 1927 71.4000°F
10.)2000 71.4000°F

Rainfall Total
2.87 Inches of Rain

1895-2011 Spring Rainfall
Mean
10.66

Median
10.17

Standard Deviation
4.49

Percentile
5th
4.32

25th
7.16

50th
10.17

75th
13.25

95th
19.00

Spring 2001 rainfall is 7.79 inches below normal. Spring 2011 is the second driest on record for the Upper Texas Coast. Here is where Spring 2011 rainfall total ranks.
1.) 2003 2.56
2.) 2011 2.87
3.) 1963 2.91
4.) 1996 3.13
5.) 1978 3.26
6.) 1998 3.32
7.) 1960 4.57
8.) 1899 5.02
9.) 1958 5.30
10.)1961 5.33

What does summer rainfall hold? There is no correlation between spring and summer rainfall total as shown in this scatter chart.

Here is the correlation value from 1895 to 2010.
r = 0.02
p-value = 0.82

There is no correlation between spring and summer rain. It could either be wet or dry summer. Interesting to note that some of the driest spring on record gave way to really wet summers. Here are summer totals following dry springs.
1.) 2003 16.91
2.) 2011 NA
3.) 1963 9.87
4.) 1996 18.4
5.) 1978 12.14
6.) 1998 11.13
7.) 1960 24.46*
8.) 1899 15.09
9.) 1958 7.87
10.)1961 23.06*

*Top 10 Wettest Summer

Some of the wettest summers on record for Upper Texas Coast occurred after a dry spring, 1960 and 1961 had wet summers in the top 10 wettest summers on record. So, not all is lost. Perhaps, we could see a wet summer. So there is hope that summer could be wet. As they say in Texas, droughts end in floods. Let’s see what happened following dry springs.
2003 Hurricane Claudette and Tropical Storm Grace make landfall.
1963 Hurricane Cindy makes landfall in East Texas. Dumps up to 23.5 inches of rain in Deweyville, Texas.
1996 Heavy rain falls in August from the outer bands of Hurricane Dolly.
1978 Hurricane Debra makes landfall in Cameron Parish, Louisiana.
1998 Tropical Storm Charley and Frances make landfall on Upper Texas Coast. Charley dumps 4 to 6 inches of rain, while Frances dumps up to 20 inches of rain.
1960 Tropical Storm #1 makes landfall in South Texas. Up to 30 inches of rain falls in Port Lavaca, Texas.
1899 A massive flood plagues the Brazos River Valley from June 27 to July 1.
1958 None
1961 Hurricane Carla makes landfall around Port Lavaca.

Here are the top 10 wettest summer for the Upper Texas Coast.
1.) 1960 24.46
2.) 1981 24.06
3.) 2007 24.01
4.) 2001 23.16
5.) 1942 23.10
6.) 1961 23.06
7.) 1919 22.82
8.) 1983 21.93
9.) 1945 21.66
10.) 1973 21.49

Source
NOAA Divisional Weather