Summary
The Pacific Northwest Index (PNI), developed by Ebbesmeyer and Strickland (1995), is a terrestrial climate index useful for studying climate effects on salmon productivity trends. It is a composite index that characterizes Pacific Northwest climate patterns in both coastal waters and freshwater habitats. In addition, it is a century-long record. A composite climate index is an effective measurement because many environmental parameters in the Northwest are statistically related to one another; consequently, they may be combined to furnish a broad-scale understanding of the state of the Pacific Northwest environment. The PNI uses three parameters: 1) air temperature at Olga in the San Juan Islands, averaged annually from daily data; 2) total precipitation at Cedar Lake in the Cascade Mountains; and 3) snowpack depth at Paradise on Mount Rainier on March 15 of each year. For each parameter, annual values were normalized by subtracting the annual value from the average of all years and dividing by the standard deviation. The sign of the normalized temperature is reversed because low temperature corresponds with high precipitation and snow. Finally, the three variables are averaged yearly giving a relative indicator of the variations in climate. Years with positive values of the PNI are warmer and drier than average and those with negative values are cooler and wetter than average.
Reference
Ebbesmeyer, C.C. and R.M. Strickland. 1995. Oyster Condition and Climate: Evidence from Willapa Bay. Publication WSG-MR 95-02, Washington Sea Grant Program, University of Washington, Seattle, WA. 11p.
Method
Annual PNI for Year Y:
PNIy = ( TempDevy + PrecipDevy + SnowDevy ) / 3
where:
- TempDevy = - ( MeanTemp - Tempy ) / StDevTemp
- PrecipDevy = ( MeanPrecip - Precipy ) / StDevPrecip
- SnowDevy = ( MeanSnow - Snowy ) / StDevSnow
Sign of TempDev is reversed because low temperature corresponds with high precipitation and snow.
Data
| Year | Olga, San Juan Islands, WA, Annual Mean Air Temperature (F) Mean 50.090 Standard Deviation 1.337 |
Temperature Deviate | Cedar Lake, WA, Total Annual Precipitation (Inches) Mean 101.774 Standard Deviation 17.541 |
Precipitation Deviate | Paradise Ranger Station, Mt Rainier, WA, Snow Pack on March 15 (Inches) Mean 170.505 Standard Deviation 53.039 |
Snow Deviate | Year | Annual PNI | 5 Year Running Average |
|---|---|---|---|---|---|---|---|---|---|
| Year | Olga, San Juan Islands, WA, Annual Mean Air Temperature (F) Mean 50.090 Standard Deviation 1.337 |
Temperature Deviate | Cedar Lake, WA, Total Annual Precipitation (Inches) Mean 101.774 Standard Deviation 17.541 |
Precipitation Deviate | Paradise Ranger Station, Mt Rainier, WA, Snow Pack on March 15 (Inches) Mean 170.505 Standard Deviation 53.039 |
Snow Deviate | Year | Annual PNI | 5 Year Running Average |
| 2015 | 54.639 | 3.401 | 102.010 | -0.013 | 58.000 | 2.121 | 2015 | 1.836 | |
| 2014 | 53.250 | 2.363 | 121.300 | -1.113 | 150.980 | 0.368 | 2014 | 0.539 | |
| 2013 | 49.400 | -0.516 | 90.090 | 0.666 | 162.000 | 0.160 | 2013 | 0.103 | 0.543 |
| 2012 | 48.870 | -0.913 | 64.980 | 2.098 | 204.020 | -0.632 | 2012 | 0.184 | 0.285 |
| 2011 | 49.010 | -0.808 | 74.410 | 1.560 | 202.000 | -0.594 | 2011 | 0.053 | 0.164 |
| 2010 | 51.660 | 1.174 | 103.350 | -0.090 | 141.000 | 0.556 | 2010 | 0.547 | -0.047 |
| 2009 | 48.073 | -1.509 | 84.230 | 1.000 | 154.000 | 0.311 | 2009 | -0.066 | -0.067 |
| 2008 | 47.538 | -1.909 | 105.140 | -0.192 | 211.000 | -0.763 | 2008 | -0.955 | -0.223 |
| 2007 | 49.103 | -0.738 | 93.600 | 0.466 | 142.000 | 0.537 | 2007 | 0.088 | -0.161 |
| 2006 | 50.497 | 0.304 | 135.420 | -1.918 | 201.000 | -0.575 | 2006 | -0.730 | 0.032 |
| 2005 | 51.882 | 1.340 | 125.341 | -1.344 | 34.000 | 2.574 | 2005 | 0.857 | 0.369 |
| 2004 | 52.391 | 1.720 | 85.490 | 0.928 | 168.000 | 0.047 | 2004 | 0.899 | 0.365 |
| 2003 | 51.000 | 0.680 | 87.621 | 0.807 | 133.000 | 0.707 | 2003 | 0.731 | 0.681 |
| 2002 | 50.608 | 0.387 | 87.218 | 0.830 | 224.000 | -1.009 | 2002 | 0.069 | 0.595 |
| 2001 | 50.451 | 0.270 | 84.532 | 0.983 | 102.000 | 1.292 | 2001 | 0.848 | 0.302 |
| 2000 | 50.372 | 0.211 | 77.640 | 1.376 | 187.000 | -0.311 | 2000 | 0.425 | 0.213 |
| 1999 | 50.611 | 0.389 | 105.060 | -0.187 | 271.000 | -1.895 | 1999 | -0.564 | 0.095 |
| 1998 | 51.351 | 0.943 | 104.790 | -0.172 | 166.000 | 0.085 | 1998 | 0.285 | -0.078 |
| 1997 | 51.145 | 0.789 | 114.060 | -0.700 | 258.000 | -1.650 | 1997 | -0.520 | -0.047 |
| 1996 | 49.511 | -0.433 | 113.640 | -0.676 | 114.000 | 1.065 | 1996 | -0.015 | 0.273 |
| 1995 | 52.085 | 1.492 | 98.610 | 0.180 | 167.000 | 0.066 | 1995 | 0.579 | 0.401 |
| 1994 | 51.611 | 1.137 | 81.200 | 1.173 | 128.000 | 0.801 | 1994 | 1.037 | 0.749 |
| 1993 | 50.756 | 0.498 | 78.000 | 1.355 | 122.000 | 0.915 | 1993 | 0.923 | 0.798 |
| 1992 | 52.153 | 1.542 | 81.590 | 1.151 | 119.000 | 0.971 | 1992 | 1.221 | 0.587 |
| 1991 | 50.696 | 0.453 | 98.520 | 0.186 | 168.000 | 0.047 | 1991 | 0.229 | 0.413 |
| 1990 | 50.857 | 0.573 | 131.740 | -1.708 | 186.000 | -0.292 | 1990 | -0.476 | 0.282 |
| 1989 | 50.471 | 0.285 | 95.000 | 0.386 | 179.000 | -0.160 | 1989 | 0.170 | 0.251 |
| 1988 | 50.637 | 0.409 | 108.490 | -0.383 | 130.000 | 0.764 | 1988 | 0.263 | 0.306 |
| 1987 | 51.693 | 1.198 | 73.890 | 1.590 | 148.000 | 0.424 | 1987 | 1.071 | 0.503 |
| 1986 | 50.837 | 0.558 | 103.990 | -0.126 | 114.000 | 1.065 | 1986 | 0.499 | 0.564 |
| 1985 | 48.825 | -0.946 | 64.280 | 2.137 | 152.000 | 0.349 | 1985 | 0.513 | 0.573 |
| 1984 | 50.980 | 0.665 | 92.080 | 0.553 | 160.000 | 0.198 | 1984 | 0.472 | 0.295 |
| 1983 | 51.324 | 0.922 | 103.680 | -0.109 | 164.000 | 0.123 | 1983 | 0.312 | 0.401 |
| 1982 | 50.151 | 0.045 | 104.400 | -0.150 | 216.000 | -0.858 | 1982 | -0.321 | 0.356 |
| 1981 | 51.818 | 1.292 | 102.990 | -0.069 | 72.000 | 1.857 | 1981 | 1.027 | 0.420 |
| 1980 | 50.605 | 0.385 | 96.860 | 0.280 | 160.000 | 0.198 | 1980 | 0.288 | 0.479 |
| 1979 | 51.123 | 0.772 | 84.370 | 0.992 | 138.000 | 0.613 | 1979 | 0.792 | 0.630 |
| 1978 | 51.025 | 0.699 | 88.770 | 0.741 | 150.000 | 0.387 | 1978 | 0.609 | 0.422 |
| 1977 | 50.230 | 0.104 | 99.990 | 0.102 | 112.000 | 1.103 | 1977 | 0.436 | 0.183 |
| 1976 | 49.893 | -0.148 | 91.480 | 0.587 | 196.000 | -0.481 | 1976 | -0.014 | -0.177 |
| 1975 | 49.129 | -0.719 | 127.180 | -1.448 | 200.000 | -0.556 | 1975 | -0.908 | -0.240 |
| 1974 | 49.937 | -0.115 | 120.550 | -1.070 | 268.000 | -1.838 | 1974 | -1.008 | -0.604 |
| 1973 | 49.362 | -0.545 | 93.300 | 0.483 | 121.000 | 0.933 | 1973 | 0.291 | -0.879 |
| 1972 | 48.429 | -1.242 | 120.460 | -1.065 | 268.000 | -1.838 | 1972 | -1.382 | -0.673 |
| 1971 | 48.562 | -1.143 | 121.530 | -1.126 | 271.000 | -1.895 | 1971 | -1.388 | -0.543 |
| 1970 | 49.395 | -0.520 | 97.600 | 0.238 | 136.000 | 0.651 | 1970 | 0.123 | -0.577 |
| 1969 | 49.315 | -0.580 | 88.760 | 0.742 | 236.000 | -1.235 | 1969 | -0.358 | -0.335 |
| 1968 | 49.661 | -0.321 | 112.540 | -0.614 | 102.000 | 1.292 | 1968 | 0.119 | -0.073 |
| 1967 | 50.148 | 0.043 | 92.470 | 0.530 | 228.000 | -1.084 | 1967 | -0.170 | -0.065 |
| 1966 | 50.016 | -0.056 | 100.940 | 0.048 | 183.000 | -0.236 | 1966 | -0.081 | -0.249 |
| 1965 | 49.534 | -0.416 | 85.590 | 0.923 | 171.000 | -0.009 | 1965 | 0.166 | -0.121 |
| 1964 | 48.425 | -1.245 | 126.160 | -1.390 | 234.000 | -1.197 | 1964 | -1.278 | -0.036 |
| 1963 | 50.293 | 0.151 | 90.740 | 0.629 | 91.000 | 1.499 | 1963 | 0.760 | -0.088 |
| 1962 | 49.559 | -0.397 | 87.620 | 0.807 | 152.000 | 0.349 | 1962 | 0.253 | -0.150 |
| 1961 | 50.449 | 0.268 | 111.230 | -0.539 | 210.000 | -0.745 | 1961 | -0.339 | -0.028 |
| 1960 | 49.243 | -0.634 | 103.170 | -0.080 | 156.000 | 0.273 | 1960 | -0.147 | -0.071 |
| 1959 | 49.239 | -0.637 | 123.690 | -1.249 | 177.000 | -0.122 | 1959 | -0.670 | -0.116 |
| 1958 | 52.241 | 1.608 | 103.640 | -0.106 | 163.000 | 0.142 | 1958 | 0.548 | -0.362 |
| 1957 | 49.340 | -0.561 | 86.160 | 0.890 | 184.000 | -0.254 | 1957 | 0.025 | -0.613 |
| 1956 | 48.574 | -1.134 | 102.610 | -0.048 | 357.000 | -3.516 | 1956 | -1.566 | -0.602 |
| 1955 | 46.888 | -2.395 | 123.600 | -1.244 | 201.000 | -0.575 | 1955 | -1.405 | -0.815 |
| 1954 | 48.847 | -0.930 | 104.510 | -0.156 | 210.000 | -0.745 | 1954 | -0.610 | -0.705 |
| 1953 | 50.556 | 0.348 | 133.000 | -1.780 | 177.000 | -0.122 | 1953 | -0.518 | -0.473 |
| 1952 | 49.396 | -0.519 | 62.360 | 2.247 | 1952 | 0.576 | -0.418 | ||
| 1951 | 48.936 | -0.863 | 99.060 | 0.155 | 198.000 | -0.518 | 1951 | -0.409 | -0.363 |
| 1950 | 47.819 | -1.699 | 131.410 | -1.690 | 1950 | -1.129 | -0.451 | ||
| 1949 | 48.640 | -1.085 | 100.220 | 0.089 | 1949 | -0.332 | -0.621 | ||
| 1948 | 48.459 | -1.220 | 121.800 | -1.142 | 198.000 | -0.518 | 1948 | -0.960 | -0.684 |
| 1947 | 50.296 | 0.154 | 114.020 | -0.698 | 185.000 | -0.273 | 1947 | -0.273 | -0.538 |
| 1946 | 49.455 | -0.475 | 111.750 | -0.569 | 231.000 | -1.141 | 1946 | -0.728 | -0.295 |
| 1945 | 49.655 | -0.326 | 124.480 | -1.294 | 148.000 | 0.424 | 1945 | -0.399 | -0.048 |
| 1944 | 50.295 | 0.153 | 79.640 | 1.262 | 105.000 | 1.235 | 1944 | 0.883 | 0.128 |
| 1943 | 49.429 | -0.495 | 81.060 | 1.181 | 163.000 | 0.142 | 1943 | 0.276 | 0.582 |
| 1942 | 50.636 | 0.408 | 98.540 | 0.184 | 105.000 | 1.235 | 1942 | 0.609 | 0.906 |
| 1941 | 52.488 | 1.793 | 81.860 | 1.135 | 81.000 | 1.688 | 1941 | 1.539 | 0.739 |
| 1940 | 52.216 | 1.589 | 83.390 | 1.048 | 116.000 | 1.028 | 1940 | 1.222 | 0.823 |
| 1939 | 51.201 | 0.830 | 94.780 | 0.399 | 228.000 | -1.084 | 1939 | 0.048 | 0.627 |
| 1938 | 50.714 | 0.466 | 81.010 | 1.184 | 147.000 | 0.443 | 1938 | 0.698 | 0.261 |
| 1937 | 49.677 | -0.309 | 114.780 | -0.741 | 174.000 | -0.066 | 1937 | -0.372 | 0.091 |
| 1936 | 49.352 | -0.552 | 98.860 | 0.166 | 196.000 | -0.481 | 1936 | -0.289 | 0.223 |
| 1935 | 49.627 | -0.347 | 79.960 | 1.244 | 159.000 | 0.217 | 1935 | 0.371 | -0.196 |
| 1934 | 51.962 | 1.400 | 112.330 | -0.602 | 100.000 | 1.329 | 1934 | 0.709 | -0.338 |
| 1933 | 48.412 | -1.255 | 138.310 | -2.083 | 216.000 | -0.858 | 1933 | -1.399 | -0.163 |
| 1932 | 48.871 | -0.912 | 133.130 | -1.788 | 200.000 | -0.556 | 1932 | -1.085 | -0.074 |
| 1931 | 50.825 | 0.549 | 103.180 | -0.080 | 102.000 | 1.292 | 1931 | 0.587 | -0.132 |
| 1930 | 49.371 | -0.538 | 72.220 | 1.685 | 101.000 | 1.310 | 1930 | 0.819 | 0.326 |
| 1929 | 49.734 | -0.267 | 74.700 | 1.543 | 172.000 | -0.028 | 1929 | 0.416 | 0.487 |
| 1928 | 51.419 | 0.993 | 87.000 | 0.842 | 126.000 | 0.839 | 1928 | 0.892 | 0.636 |
| 1927 | 50.375 | 0.213 | 111.220 | -0.538 | 198.000 | -0.518 | 1927 | -0.281 | 0.540 |
| 1926 | 53.011 | 2.184 | 89.850 | 0.680 | 110.000 | 1.141 | 1926 | 1.335 | 0.462 |
| 1925 | 51.855 | 1.320 | 90.600 | 0.637 | 220.000 | -0.933 | 1925 | 0.341 | 0.209 |
| 1924 | 49.783 | -0.230 | 97.320 | 0.254 | 168.000 | 0.047 | 1924 | 0.024 | 0.204 |
| 1923 | 50.019 | -0.053 | 100.210 | 0.089 | 232.000 | -1.159 | 1923 | -0.375 | -0.268 |
| 1922 | 48.515 | -1.178 | 92.750 | 0.514 | 184.000 | -0.254 | 1922 | -0.306 | -0.408 |
| 1921 | 49.118 | -0.727 | 128.000 | -1.495 | 216.000 | -0.858 | 1921 | -1.027 | -0.593 |
| 1920 | 49.477 | -0.459 | 124.000 | -1.267 | 136.000 | 0.651 | 1920 | -0.358 | -0.574 |
| 1919 | 49.203 | -0.664 | 111.800 | -0.572 | 248.000 | -1.461 | 1919 | -0.899 | -0.775 |
| 1918 | 50.471 | 0.285 | 118.280 | -0.941 | 180.000 | -0.179 | 1918 | -0.278 | -0.767 |
| 1917 | 49.220 | -0.651 | 137.800 | -2.054 | 236.000 | -1.235 | 1917 | -1.313 | -0.614 |
| 1916 | 47.749 | -1.751 | 113.250 | -0.654 | 200.000 | -0.556 | 1916 | -0.987 | -0.367 |
| 1915 | 51.644 | 1.162 | 100.650 | 0.064 | 1915 | 0.409 | -0.326 | ||
| 1914 | 50.764 | 0.504 | 93.100 | 0.494 | 1914 | 0.333 | -0.069 | ||
| 1913 | 49.356 | -0.549 | 95.800 | 0.341 | 1913 | -0.070 | 0.107 | ||
| 1912 | 50.019 | -0.053 | 102.400 | -0.036 | 1912 | -0.030 | -0.087 | ||
| 1911 | 48.885 | -0.901 | 91.650 | 0.577 | 1911 | -0.108 | -0.263 | ||
| 1910 | 49.027 | -0.795 | 117.250 | -0.882 | 1910 | -0.559 | -0.327 | ||
| 1909 | 47.934 | -1.613 | 102.280 | -0.029 | 1909 | -0.547 | -0.298 | ||
| 1908 | 49.945 | -0.109 | 120.560 | -1.071 | 1908 | -0.393 | -0.355 | ||
| 1907 | 49.481 | -0.456 | 87.530 | 0.812 | 1907 | 0.119 | -0.283 | ||
| 1906 | 50.803 | 0.533 | 131.990 | -1.723 | 1906 | -0.397 | -0.127 | ||
| 1905 | 50.209 | 0.089 | 113.640 | -0.676 | 1905 | -0.196 | -0.130 | ||
| 1904 | 50.235 | 0.108 | 91.390 | 0.592 | 1904 | 0.233 | -0.137 | ||
| 1903 | 49.336 | -0.564 | 113.440 | -0.665 | 1903 | -0.410 | -0.069 | ||
| 1902 | 50.434 | 0.257 | 1902 | 0.086 | -0.124 | ||||
| 1901 | 49.863 | -0.170 | 1901 | -0.057 | -0.360 | ||||
| 1900 | 49.673 | -0.312 | 121.150 | -1.105 | 1900 | -0.472 | -0.335 | ||
| 1899 | 48.401 | -1.263 | 129.360 | -1.573 | 1899 | -0.945 | -0.393 | ||
| 1898 | 48.942 | -0.859 | 1898 | -0.286 | -0.437 | ||||
| 1897 | 49.277 | -0.608 | 1897 | -0.203 | -0.316 | ||||
| 1896 | 48.973 | -0.836 | 1896 | -0.279 | -0.167 | ||||
| 1895 | 50.615 | 0.392 | 1895 | 0.131 | -0.222 | ||||
| 1894 | 49.288 | -0.600 | 1894 | -0.200 | -0.044 | ||||
| 1893 | 47.847 | -1.678 | 1893 | -0.559 | 0.184 | ||||
| 1892 | 52.837 | 2.054 | 1892 | 0.685 | |||||
| 1891 | 53.559 | 2.594 | 1891 | 0.865 |