AgWeatherNet 2011 Weather Review for Washington

The Weather Lagged the Calendar During Much of 2011

Nic Loyd, Meteorologist, 509-786-9357
Gerrit Hoogenboom, Director, 509-786-9371

Overview
2011 was a remarkable year in which unusual weather events were commonplace and even expected. Temperatures in Washington were generally cooler than average, although there was significant inter-seasonal variability. Spring and early summer were cooler than average, while late summer and early fall were warmer than average. The year began with warmer than normal conditions and relatively little mountain snowfall during January. Although the presence of a moderate to strong La Niña during the autumn of 2010 led to the expectation of a cool and wet spring, no one could have predicted that central Washington would experience the coolest and windiest spring in recent memory. The magnitude of the chill was surprising as some locations observed high temperatures that were more than five degrees below normal for the month of April. The cool conditions lingered into July, before typical summertime warmth returned in August. However, in another meteorological surprise, summer proved that it would merely be late and not absent in Washington. Many locations experienced near record heat during early to mid September during what was by far the most significant heat wave of the year. 2011 ended as unexpectedly as it had begun, with remarkably dry and calm conditions for much of December. Overall, temperatures at the WSU Prosser facilities (IAREC) were around one degree below average for the year.

2011 Daily Average Temperatures and Total Precipitation
Location Maximum (°F) Mean (°F) Minimum (°F) Precip (")
Prosser
62.4
50.7
39.1
4.66
Moxee
62.0
48.2
33.7
5.35
Mt. Vernon
57.1
49.4
42.3
30.08
Wenatchee
61.2
50.2
39.6
8.71
Tri-Cities
64.4
52.8
41.0
3.24
Walla Walla
62.1
52.1
42.4
16.19
Royal City East
60.1
49.6
39.8
4.26
Pullman
56.0
45.9
35.2
16.25

The Year in Review-2011 Weather
Early 2011-A Record Cool Spring
Following the record cold of late November 2010, January of 2011 was generally much warmer than normal across the state. Many locations experienced several days in mid January and mid February with temperatures in the 60s. However, the warmth did not last for long. Just as the winter had begun, arctic air invaded the region in late February, bringing the coldest weather of 2011 at the end of the winter season. This unusual event heralded in a significant pattern change. The spring was cooler and wetter than normal, with only one heat wave occurring on April 1st. High temperatures in central Washington were around 5 degrees below normal in April, as many locations experienced the coolest spring in more than twenty years. Overall, springtime conditions were cool, windy, and remarkably stable due to a persistent and cold jet stream that transported cold air from the north Pacific into Washington. Mountain snowpack increased throughout the spring, which endowed growers with a plentiful water supply for summer.

Mid 2011-Summer Arrives Late
Heavy rain in mid May led to river flooding, and cooler than normal temperatures persisted into the summer. After a very cool July that featured an absence of oppressive heat, numerous sunny, hot days in August led to the first month of above normal temperatures since January. However, the warmest weather was still to come, as central Washington experienced the hottest weather of the year in early and mid September. Temperatures soared to near record levels from September 9 to 13, during which time much of central Washington recorded high temperatures above 90 degrees for five consecutive days. Orondo (north of Wenatchee) recorded a temperature of 101 degrees on September 12th, which is very late in the year for such a heat wave. October featured fairly normal conditions, although a series of weak weather systems caused normally cold valley locations to experience well above normal overnight low temperatures for the month. For example, Moxee recorded its first frost on October 24th, which is nearly a month later than normal. The late frost provided a reprieve for Washington apple growers who faced a late harvest due to the cool spring. November was typically variable, and featured rain, snow, and periods of near record warmth in the Walla Walla area.

Late 2011-A Calm December
Finally, the last month of 2011 was remarkably calm and dry by December standards thanks to a persistent ridge of high pressure over the Pacific Northwest. The month began with abundant sunshine and seasonal temperatures. Although conditions aloft were generally mild, very stable conditions led to cold temperatures, low clouds, and poor air quality in the lowlands in the early to middle part of the month. The mountains received very little snow during what is normally one of the snowiest months of the year, while areas west of the mountains observed well below normal rainfall. Overall, December was remarkable precisely because of the abnormally dry and calm conditions that prevailed until Christmas. The lack of storms in December is particularly noteworthy since La Niña conditions were present during the fall and winter of 2011, which tilts the odds toward wetter than normal conditions early in the cold season. Wet, windy, and warmer weather returned during the final week of 2011.

2011 Daily Temperatures
2011 Temp/Precip Time Seris Graphs 2011 Temp/Precip Time Series Graphs
2011 Temp/Precip Time Series Graphs 2011 Temp/Precip Time Series Graphs
2011 Temp/Precip Time Series Graphs 2011 Temp/Precip Time Series Graphs
2011 Temp/Precip Time Series Graphs
2011 Temp/Precip Time Series Graphs 2011 Temp/Precip Time Series Graphs

2011 Daily Precipitation
2011 Temp/Precip Time Seris Graphs 2011 Temp/Precip Time Series Graphs
2011 Temp/Precip Time Series Graphs 2011 Temp/Precip Time Series Graphs
2011 Temp/Precip Time Series Graphs 2011 Temp/Precip Time Series Graphs
2011 Temp/Precip Time Series Graphs
2011 Temp/Precip Time Series Graphs 2011 Temp/Precip Time Series Graphs

2011-By the Numbers
The average temperature at Prosser (WSU IAREC) for 2011 was 50.7°F, which was 1.1 degrees (about 1 standard deviation) below average. The average high temperature was 62.4°F, or 0.8 degrees below average, while the average low temperature was 39.1°F, or 1.0 degree below average. 4.66 inches of precipitation fell during the year, and the average wind speed was 4.6 mph. The warmest temperature of the year was 95.7°F recorded on August 27th, while the coldest temperature of 2011 was 7.3°F recorded on February 26th. The warmest low temperature of the year was 62°F recorded on August 25th, while the coldest high temperature of 2011 was 23.1°F recorded on December 10th. The coldest month of the year was December with an average temperature of 30.6°F, while the warmest month of the year was August with an average temperature of 70.8°F. The average high and low temperatures at Wenatchee were 61.2°F/39.6°F and at Pullman were 56.0°F /35.2°F.

Notable 2011 Weather Events:
  • February 26th: Temperatures plummeted to -14.8 degrees at Pullman. This was the coldest temperature recorded by AgWeatherNet in 2011.
  • February 28th: Winds at Huntsville gusted to 71.5 mph. This was the strongest wind gust recorded by AgWeatherNet in 2011.
  • February 28th: 15 minute sustained winds at St. John peaked at 52.9 mph. This was the strongest sustained wind recorded by AgWeatherNet in 2011.
  • March 31st: The daily average wind speed at St. John was 27.7 mph. This was the highest daily average wind speed recorded by AgWeatherNet in 2011.
  • April 1st: Temperatures soared above 80 degrees for the first and only time during the spring season at Prosser (WSU IAREC).
  • May 14th: 0.9 inches of rain fell in less than 24 hours at Prosser (WSU IAREC).
  • July 25th: 0.23 inches of rain fell in only 15 minutes in association with a thunderstorm at Prosser (WSU IAREC).
  • August 27th: Temperatures soared to 101.5 degrees at Orondo (north of Wenatchee). This was the warmest temperature recorded by AgWeatherNet in 2011.
  • November 22nd: 3.1 inches of rain fell at Montesano. This was the highest daily precipitation amount recorded by AgWeatherNet in 2011.
  • December 28th: Temperatures overnight fell to only 51 degrees at Prosser (WSU IAREC).

The seasons in 2011 seemed to be delayed by one month or more, which led to an unusual distribution of temperatures throughout the year. Spring weather persisted into June and even July, while summer heat peaked very late in early to mid September, and frost did not come to central Washington until late October. Although there is no such thing as an “average” year, we outline several examples of why 2011 featured more than its fair share of weather abnormalities in Washington:

  • The monthly average low temperature was colder in February than in January and colder in April than in March.
  • The average high temperature in August was four and a half degrees warmer than in July, despite the fact that July is normally the warmest month of the year.
  • The average high temperature in September was more than five degrees warmer than the average June high temperature, although June is normally slightly warmer. While it failed to reach 90 degrees at Prosser (WSU IAREC) in June for only the third time since 1990, there were seven days with temperatures above 90 degrees in September.
  • The average high temperature was nearly five degrees warmer in October than in April, despite the fact that April's high temperature is typically slightly warmer. Also, the average low temperature was around seven and a half degrees warmer in October than in April, even though the low temperature is typically similar between the two months.
  • Cascade Mountain snowfall, especially at mid to high elevations on the west slopes, was much higher in March and April than in January. In fact, Paradise, Mt. Rainier experienced its snowiest April on record.

2011 Temp/Precip Time Series Graphs

Annual Temperature Extremes
  Observed in 2011 Record Annual Extremes
Site (Period of Record) Warmest (°F) Date Coldest (°F) Date Warmest (°F) Date Coldest (°F) Date
Prosser (WSU IAREC; 1989-2011)
95.7
8/27/2011
7.3
2/26/2011
109.9
7/12/2002
-13.0
2/3/1996
Moxee (1989-2011)
97.2
9/12/2011
3.3
2/26/2011
107.5
7/12/2002
-22.7
1/31/1996
Mt. Vernon (WSU NWREC; 1994-2011)
81.0
9/4/2011
7.8
2/26/2011
96.1
7/29/2009
7.5
11/28/2006
Wenatchee (WSU TFREC; 1994-2011)
98.8
9/9/2011
4.7
2/25/2011
106.7
7/23/2006
-13.4
1/30/1996
Tri-Cities (1995-2011
99.6
8/28/2011
8.3
2/25/2011
110.1
7/23/2006
-10.8
2/2/1996
Walla Walla (1992-2011)
98.7
8/27/2011
6.9
1/3/2011
107.3
7/12/2002
-15.0
2/1/1996
Royal City East (2008-2011)
92.6
9/9/2011
7.5
1/3/2011
101.4
8/17/2008
-3.6
11/24/2010
Pullman (2008-2011)
96.9
8/28/2011
-14.8
2/26/2011
102.2
8/17/2008
-17.5
1/26/2009
Weather Summary By Month
  • January: Above normal temperatures with highs in the 60s around mid month.
  • February: Warm conditions mid month were followed by arctic cold late in the month.
  • March: Slightly below normal temperatures and wetter than normal.
  • April: Much cooler than normal.
  • May: Much cooler and wetter than normal.
  • June: Cooler than normal.
  • July: Much cooler than normal.
  • August: Warmer than normal, especially during the day.
  • September: Well above normal temperatures with record heat from the 9th to the 13th.
  • October: Warmer than normal overnight temperatures in the valley regions.
  • November: Slightly below normal temperatures especially overnight.
  • December: Generally calm and very dry conditions.

2011 Monthly Temperatures
2011 Temp/Precip Bar Graphs 2011 Temp/Precip Bar Graphs
2011 Temp/Precip Bar Graphs 2011 Temp/Precip Bar Graphs
2011 Temp/Precip Bar Graphs 2011 Temp/Precip Bar Graphs
2011 Temp/Precip Bar Graphs
2011 Temp/Precip Bar Graphs 2011 Temp/Precip Bar Graphs

2011 Monthly Precipitation
2011 Temp/Precip Bar Graphs 2011 Temp/Precip Bar Graphs
2011 Temp/Precip Bar Graphs 2011 Temp/Precip Bar Graphs
2011 Temp/Precip Bar Graphs 2011 Temp/Precip Bar Graphs
2011 Temp/Precip Bar Graphs
2011 Temp/Precip Bar Graphs 2011 Temp/Precip Bar Graphs

Agriculture Report
The unusual weather in 2011 had a particularly significant negative impact upon Washington farmers and growers. The U.S. Department of Agriculture (USDA) has designated 15 Washington counties as primary natural disaster areas, while 20 counties were named contiguous disaster counties. Farmers in these counties across the state will be eligible for emergency assistance related to agricultural losses that were caused by extreme weather from January 1 to July 31, 2011. Tree fruits, vegetables, grapes, hay, and wheat were particularly impacted. (http://cantwell.senate.gov/news/record.cfm?id=335682).

Cold temperatures in late November of 2010 caused a 15% to 25% reduction in vineyard production for central Washington in 2011. Despite a cool spring and a delayed development, the apple crop was large and of good quality. Other tree fruit also fared well despite unusual weather conditions. An unusually late first frost in central Washington allowed most of the harvest to be completed without damage to the apples. The harvest of Christmas trees was easy due to the dry and calm December weather. At the end of 2011, winter wheat was in good to excellent condition in eastern Washington, although there is concern that the dry winter up to the end of December could ultimately limit the crop (National Agricultural Statistics Service).

Weather History
Despite the cool spring in 2011, the temperatures were pale in comparison to the unusual year of 1993, which was generally the coolest year since 1990 in central Washington. In fact, five months in 1993 earn the distinction as the coldest month on record at Prosser (WSU IAREC) for the 1990 to 2011 time period. The coolest January, February, March, July, and November occurred in 1993. The average temperature of 24.5 degrees made January 1993 the overall coldest month on record. By contrast, 1992 was the warmest year in recent times.

Climate Outlook
The Climate Prediction Center’s long term outlook calls for normal conditions in February, and then below normal temperatures and above normal precipitation for the spring season. During late summer and early autumn, long term trends tilt the odds toward warmer and drier than normal conditions.

Washington State University