Maps of U.S. Winter Precipitation and Temperature Ranks and Departures

Maps of U.S. Winter Precipitation and Temperature Ranks and Departures

(These maps generated using analysis software at CDC-CIRES in Boulder. Thank you to them!)



El Nino Maps. (La Nina and "All Years" maps are farther below.)

Winter Precipitation (Oct-Mar) Rank for Recent El Nino Years

These maps show the rank of October through March precipitation with respect to all winters from 1895-1997. Reddish colors are among the lowest precipitation and bluish colors are among the highest precipitation. The scale ranges from 0 (driest) to 100 (wettest). Note that the year shown on the graph is the starting year if there is ambiguity in this regard. El Nino years only.

Based on Pre-1931 Divisional Data:
1905-06, 1914-15, 1918-19, 1925-26,
Based on Post-1931 Divisional Data:
1940-41, 1957-58, 1965-66, 1972-73, 1977-78, 1982-83, 1987-88, 1991-92, 1992-93, 1993-94, 1994-95

Details of individual years, for several major El Ninos.

The main message. "El Nino winters" vary considerably from winter to winter, and within the individual winters themselves."
1940-1941: Oct, Nov, Dec, Jan, Feb, Mar, Apr
1957-1958: Oct, Nov, Dec, Jan, Feb, Mar, Apr
1972-1973: Oct, Nov, Dec, Jan, Feb, Mar, Apr
1982-1983: Oct, Nov, Dec, Jan, Feb, Mar, Apr

Composite of U.S. October-March precipitation for nine El Nino years since 1940. Departures from 1950-1995 means expressed in terms of standard deviations. The years are 1940-41, 57-58, 65-66, 72-73, 77-78, 82-83, 87-88, 91-92, 94-95.

La Nina Maps. ("All Years" maps are farther below.)

Composite Maps for 10 Positive SOI ("La Nina") Years Since 1950
(Uses Atmospheric Criteria instead of Ocean Criteria that CPC uses):
1950-51,1955-56,1956-57,1964-65,1970-71,1971-72,1973-74,1974-75,1975-76,1988-89


1. Precipitation Departure from 1950-95 Mean, Standardized Anomalies (Standard Deviations)
Oct-Mar (Entire Winter)
Oct-Dec (Early Winter)
Jan-Mar (Late Winter)
Nov-Feb (Middle Winter)
Individual Months:
Oct, Nov, Dec, Jan, Feb, Mar

2. Temperature Departure from 1950-95 Mean, Standardized Anomalies (Standard Deviations)
Oct-Mar (Entire Winter)
Oct-Dec (Early Winter)
Jan-Mar (Late Winter)
Nov-Feb (Middle Winter)
Individual Months
Oct, Nov, Dec, Jan, Feb, Mar

3. Precipitation Departure from 1950-95 Mean, Average Anomalies (Units Inches)
Oct-Mar (Entire Winter)
Oct-Dec (Early Winter)
Jan-Mar (Late Winter)
Nov-Feb (Middle Winter)
Individual Months:
Oct, Nov, Dec, Jan, Feb, Mar

4. Temperature Departure from 1950-95 Mean, Average Anomalies (Units: Degrees F)
Oct-Mar (Entire Winter)
Oct-Dec (Early Winter)
Jan-Mar (Late Winter)
Nov-Feb (Middle Winter)
Individual Months:
Oct, Nov, Dec, Jan, Feb, Mar

Composite Maps for 7 La Nina Years Selected by Climate Predition Center
(Uses Ocean Criteria instead of Atmospheric Criteria as above):
1942-43, 1950-51,1955-56,1970-71,1973-74,1975-76,1988-89


1. Precipitation Departure from 1950-95 Mean, Standardized Anomalies (Standard Deviations)
Oct-Mar (Entire Winter)
Oct-Dec (Early Winter)
Jan-Mar (Late Winter)
Nov-Feb (Middle Winter)
Oct, Nov, Dec, Jan, Feb, Mar

2. Temperature Departure from 1950-95 Mean, Standardized Anomalies (Standard Deviations)
Oct-Mar (Entire Winter)
Oct-Dec (Early Winter)
Jan-Mar (Late Winter)
Nov-Feb (Middle Winter)
Individual Months
Oct, Nov, Dec, Jan, Feb, Mar

3. Precipitation Departure from 1950-95 Mean, Average Anomalies (Units Inches)
Oct-Mar (Entire Winter)
Oct-Dec (Early Winter)
Jan-Mar (Late Winter)
Nov-Feb (Middle Winter)
Individual Months
Oct, Nov, Dec, Jan, Feb, Mar

4. Temperature Departure from 1950-95 Mean, Average Anomalies (Units: Degrees F)
Oct-Mar (Entire Winter)
Oct-Dec (Early Winter)
Jan-Mar (Late Winter)
Nov-Feb (Middle Winter)
Individual Months
Oct, Nov, Dec, Jan, Feb, Mar

Winter Precipitation (Oct-Mar) Rank for Recent La Nina Years

These maps show the rank of October through March precipitation with respect to all winters from 1895-1998. Reddish colors are among the lowest precipitation and bluish colors are among the highest precipitation. The scale ranges from 0 (driest) to 100 (wettest). Note that the year shown on the graph is the starting year if there is ambiguity in this regard. Major La Nina (Positive Southern Oscillation Index) years only.

Based on Pre-1931 Divisional Data:
1886-87, 1906-07, 1910-11, 1916-17, 1917-18, 1923-24,
Based on Post-1931 Divisional Data:
1938-39, 1950-51, 1955-56, 1973-74, 1975-76, 1988-89, 1996-97


next section not yet completed--disregard
Details of individual years, for several major La Ninas.

Like El Nino winters, "La Nina winters" vary considerably from winter to winter, and within the individual winters themselves."
1950-51: Oct, Nov, Dec, Jan, Feb, Mar, Apr
1955-56: Oct, Nov, Dec, Jan, Feb, Mar, Apr
1973-74: Oct, Nov, Dec, Jan, Feb, Mar, Apr
1975-76: Oct, Nov, Dec, Jan, Feb, Mar, Apr
1988-89: Oct, Nov, Dec, Jan, Feb, Mar, Apr

All Years Maps.

Winter (Oct-Mar) Precipitation Rank (All Years since 1940)

These maps show the ranking of each individual winter (October through March) precipitation from the perspective of all winters from 1895 to 1997. Note that the year shown on the graph is the starting year if there is ambiguity in this regard.

1940-41, 1941-42, 1942-43, 1943-44, 1944-45, 1945-46, 1946-47, 1947-48, 1948-49, 1949-50
1950-51, 1951-52, 1952-53, 1953-54, 1954-55, 1955-56, 1956-57, 1957-58, 1958-59, 1959-60
1960-61, 1961-62, 1962-63, 1963-64, 1964-65, 1965-66, 1966-67, 1967-68, 1968-69, 1969-70
1970-71, 1971-72, 1972-73, 1973-74, 1974-75, 1975-76, 1976-77, 1977-78, 1978-79, 1979-80
1980-81, 1981-82, 1982-83, 1983-84, 1984-85, 1985-86, 1986-87, 1987-88, 1988-89, 1989-90
1990-91, 1991-92, 1992-93, 1993-94, 1994-95, 1995-96, 1996-97 1997-98


Winter (Oct-Mar) Temperature Rank (All Years since 1930)

These maps show the ranking of each individual winter (October through March) temperature from the perspective of all winters from 1895 to 1998. Note that the year shown on the graph is the starting year if there is ambiguity in this regard.

1930-31, 1931-32, 1932-33, 1933-34, 1934-35, 1935-36, 1936-37, 1937-38, 1938-39, 1939-40
1940-41, 1941-42, 1942-43, 1943-44, 1944-45, 1945-46, 1946-47, 1947-48, 1948-49, 1949-50
1950-51, 1951-52, 1952-53, 1953-54, 1954-55, 1955-56, 1956-57, 1957-58, 1958-59, 1959-60
1960-61, 1961-62, 1962-63, 1963-64, 1964-65, 1965-66, 1966-67, 1967-68, 1968-69, 1969-70
1970-71, 1971-72, 1972-73, 1973-74, 1974-75, 1975-76, 1976-77, 1977-78, 1978-79, 1979-80
1980-81, 1981-82, 1982-83, 1983-84, 1984-85, 1985-86, 1986-87, 1987-88, 1988-89, 1989-90
1990-91, 1991-92, 1992-93, 1993-94, 1994-95, 1995-96, 1996-97 1997-98


Western Regional Climate Center, Dr. Kelly Redmond, krwrcc@dri.edu