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April weather a smorgasbord of extremes – WSU AgWeatherNet monthly report

PROSSER, Wash. – Time heals all wounds and, for many Washingtonians, the chilly and inclement weather of last spring is just a distant memory. The warmth and sunshine of late April has certainly helped to erase the memory of last spring’s record cold. That’s good news for growers and gardeners. “Despite periods of unusual weather during April, Washington crops generally fared well in the mild conditions, and no significant, weather-related agricultural losses were reported,” said Gerrit Hoogenboom, director of Washington State University’s AgWeatherNet. “The accumulated growing degree day values were above average in April and much higher than the values observed during the same time period last year.”

Heat wave

A heat wave April 22-24 featured record-breaking temperatures that peaked at around 90 degrees in central Washington on April 23. Temperatures were 20 degrees or more above normal in some cases, and balmy overnight conditions provided little relief from the heat. Cloudy, windy and humid conditions caused low temperatures to fall into the 50s to low 60s.

“Several AgWeatherNet monthly temperature records were set during the unusually early heat wave,” said AgWeatherNet meteorologist Nic Loyd. “The high temperature of 88.2 degrees on April 23 at AgWeatherNet’s Moxee weather station, near Yakima, was an April record for the station. Also, the low of 56.5 degrees at WSU Tri-Cities on April 24 was 1.5 degrees warmer than the previous warmest April daily low temperature.”

The unusually early hot spell was accompanied by thunderstorms and other abnormal weather. Nearly half an inch of rain fell in parts of southeastern Washington on the evening of April 23, while sustained winds of 50 mph were punctuated by gusts approaching 70 mph at St. John.

Flooding then freezing

Rapid snowmelt stemming from the unusual heat was followed by significant rain in parts of northeastern Washington. These factors combined to cause flooding on many eastern Washington rivers.

April 26 was a uniquely wet day across the state, including in arid central Washington. All of the nearly 140 AgWeatherNet stations recorded rain on that day, including nearly an inch of rain at Oroville and Walla Walla.

As is often the case, the summer-like heat did not stay for long in Washington. Below normal temperatures returned on April 27, including freezing temperatures in places that had been near 90 degrees a few days earlier. Snow fell in the high elevations of the Cascades on April 30.
Temperature records set

Overall, April featured a smorgasbord of weather conditions. Temperatures ranged from the teens near Ellensburg on April 7 to the low 90s in parts of central Washington on April 23.

April’s average temperature at WSU’s Irrigated Agriculture Research and Extension Center in Prosser was 53.3 degrees – 1.7 degrees above average and 6.1 degrees warmer than April 2011. The average high of 65.1 degrees was 7.1 degrees warmer than last April, while the average low of 40.5 degrees was the warmest since 1994.

Monthly temperature records were set at Prosser and at the AgWeatherNet station at WSU’s Tree Fruit Research and Extension Center in Wenatchee.

For more information about the April heat wave, as well as other weather information, visit the AgWeatherNet website. The April Weather Review is located under the News link. A Web based, publicly available system, AgWeatherNet provides access to near real-time weather data and value-added products from WSU’s statewide weather network, along with decision aids for agricultural producers and other users.

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