AgWeatherNet April 2015 Weather Review for Washington

April Temperatures Variable, But Only Slightly Above Normal

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

Overview
To say that April mean temperatures were near normal would not be newsworthy during normal times. But these are not normal times. In light of the five record warm months since last July, April represented a welcome reprieve from the recent trend. However, the drought situation has not improved from a status perspective, and has worsened from a prognostic point of view. Overall, April was a dry month, which partly explains why Prosser's high temperatures were somewhat above normal, while low temperatures were near to slightly below normal. The relative lack of clouds and moisture allowed for sunnier and warmer days, and yet cool and stable nights. In fact, the mean low was slightly lower than it was in March, which is of course a testament to the warmth of March, rather than the chill of April. Interestingly, Moxee experienced a precipitation-free April.

The first half of April was, amazingly, not that warm. There were even some days with below normal temperatures. Highs around Walla Walla were only in the 40s on April 5th, and Broadview fell to a low of 20 degrees. Later in the month, the high temperature at Thorp reached just 49 degrees on April 12th, and the low at Ritzville on the 15th was 23 degrees. On April 13th, 1.11 inches of rain fell at Long Beach on one of the wetter days of the month. However, the second half of April was highly changeable. Azwell in north central Washington reached 83 degrees on April 20th, and then Garfield East reached only 47 degrees on the 25th, and Ritzville fell to 22 degrees on April 26th. Heat returned at month's end, as Vancouver reached 81 degrees on the 27th, and Benton City climbed to 86 degrees on the 28th.

April 2015 Average Temperatures (°F)
Location (Period of Record) Maximum Anomaly Minimum Anomaly Mean Anomaly Soil Temperature
8 inches
Prosser (WSU IAREC; 1989-2015)
65.2
1.6
38.1
-0.6
52.3
0.5
55.6
Moxee (1989-2015)
64.9
1.8
31.5
-1.4
49.3
-0.1
51.0
Mt Vernon (WSU NWREC; 1994-2015)
58.8
1.7
40.7
-0.3
49.6
0.7
53.0
Wenatchee (WSU TFREC; 1994-2015)
65.1
1.7
38.8
-0.2
52.3
0.6
54.6
Tri-Cities (1995-2015)
67.6
1.7
39.7
-0.4
54.3
0.8
60.1
Walla Walla (1993-2015)
63.6
2.1
40.1
-1.1
51.8
0.4
53.3
Moses Lake (1989-2015)
64.9
2.1
37.6
-0.3
51.6
0.9
56.5
Omak (Pogue Flat; 2005-2015)
63.2
NA
37.7
NA
50.8
NA
53.8
Royal City East (2008-2015)
64.0
NA
39.7
NA
51.5
NA
54.1
Pullman (2008-2015)
57.5
NA
32.7
NA
45.5
NA
47.8
Long Beach (WSU Long Beach; 2005-2015)
56.9
NA
38.6
NA
48.1
NA
53.7
Sequim (2008-2015)
57.9
NA
37.0
NA
47.9
NA
48.9
Seattle (2011-2015)
60.8
NA
42.7
NA
51.0
NA
56.0
Vancouver (WSU RE; 2008-2015)
61.8
NA
38.6
NA
50.6
NA
54.2
2015 Rainfall and Evapotranspiration (ET) (inches)
Location (Period of Record) Rainfall ET Net
April 2015 April (Rain - ET)
Prosser (WSU IAREC; 1989-2015)
0.07
2.15
5.77
-5.70
Moxee (1989-2015)
0.00
1.74
5.50
-5.50
Mt. Vernon (WSU NWREC; 1994-2015)
1.48
11.65
3.26
-1.78
Wenatchee (WSU TFREC; 1994-2015)
0.20
3.08
4.99
-4.79
Tri-Cities (1995-2015)
0.11
2.18
6.01
-5.90
Walla Walla (1993-2015)
0.99
5.31
4.71
-3.72
Moses Lake (1989-2015)
0.16
1.97
6.00
-5.84
Omak (Pogue Flat; 2005-2015)
0.04
2.48
5.25
-5.21
Royal City East (2008-2015)
0.32
1.55
5.63
-5.31
Pullman (2008-2015)
0.40
6.75
5.39
-4.99
Long Beach (WSU Long Beach; 2005-2015)
3.16
21.82
2.90
0.26
Sequim (2008-2015)
0.40
7.12
3.22
-2.82
Seattle (2011-2015)
1.74
13.00
3.33
-1.59
Vancouver (WSU RE; 2008-2015)
1.72
12.84
3.58
-1.86
April 2015 Daily Rainfall Time Series Graph for Prosser April 2015 Daily Rainfall Time Series Graph for Long Beach

April Weather
Early April-Cool Weather
The weather was somewhat variable and rather cool during early April. Highs were generally in the 50s and 60s, with lows in the upper 20s to 40s. April 5th was a cool day for areas around Walla Walla that only climbed into the 40s, while Broadview started the day at just 20 degrees. On April 6th, the high was only 38 degrees at Green Bluff, as 0.53 inches of rain fell at St. Andrews.

Mid April-From Cool and Unsettled to Warm and Dry
A front brought more than 0.8 inches of rain to some coastal areas on April 10th, as highs were in the mid 50s to around 70 degrees, and lows were in the upper 20s to 40s. Highs on the 11th dropped to the upper 40s to low 60s, with similar lows. The daily average wind speed was 20 mph at St. John. Lows were as cool as the mid 20s on the 12th, as moderate breezes continued in the east. Another front approached on April 13th, with highs in the upper 40s to mid 50s in the west, but 60s in eastern border areas. Lows were in the upper 20s to mid 40s. Rain fell in the west, including 1.11 inches at Long Beach, as southerly winds increased.

The 14th was a cool, breezy, post-frontal day, as Garfield East reached only 45 degrees for a high temperature. The morning of the 15th was cold, with numerous 20s east of the Cascades. Temperatures warmed notably beginning on April 16th, as calmer and drier conditions prevailed. Aside from a weak storm passage early on the 18th, warm weather continued during the third week of April.

Late April-Highly Variable Conditions
Warm temperatures began the period, with a high of 83 degrees at Azwell on April 20th. Western highs cooled on the 21st, before eventually moving to the east, as slightly unsettled weather resumed. Highs on the 21st ranged from 54 degrees at Long Beach to 84 degrees at Desert Aire. Dayton NW recorded a 41 mph wind gust on the 22nd. Highs on the 23rd were again only in the 50s, except 60s in parts of central Washington. Lows were in the 30s and 40s. Rain fell in western areas, with more than a half-inch recorded at Tokeland.

Cooler weather on the 22nd transitioned to much warmer weather by the 27th. Highs on the 24th were only in the 50s to mid 60s, including 49 degrees at Underwood. Rain fell in some western areas, as eastern sites were breezy. Garfield East reached only 47 degrees on April 25th, with lows in the upper 20s to 40s. There were isolated showers and gusty winds. Lows on the 26th were as cold as 22 degrees at Ritzville, though highs warmed to the mid 50s to 60s. Highs climbed to 81 degrees at Vancouver on the 27th, and to 86 degrees at Benton City on the 28th.

April 2015 Daily Temperatures
2015 temperature Time Series Graph for Prosser 2015 temperature Time Series Graph for Moxee
2015 temperature Time Series Graph for Wenatchee 2015 temperature Time Series Graph for Tri-Cities
2015 temperature Time Series Graph for:Walla Walla April 2015 Temperature Time Series Graph for WSU
April 2015 Temperature Time Series Graph for WSUMoses Lake April 2015 Temperature Time Series Graph for WSU Omak
April 2015 Temperature Time Series Graph for WSU Long Beach April 2015 Temperature Time Series Graph for WSU Mt. Vernon

April-By The Numbers
The average April temperature at Prosser (WSU IAREC) was 52.3°F, which is 0.5 degrees above average. The average high temperature was 65.2°F, which is 1.6 degrees above average. The average low temperature was 38.1°F, which is 0.6 degrees below average. The maximum temperature recorded last month was 81.5°F on April 28th, while the coolest daily high was 50.8°F on April 5th. Low temperatures ranged from 46.8°F on April 27th to 30.7°F on April 4th. Daily average temperatures ranged from 64.0°F on the 28th to 41.9°F on the 5th. The monthly precipitation total was 0.07 inches. The average wind speed was 4.9 mph, and the average 8 inch soil temperature was 55.6°F. Wenatchee (WSU TFREC) recorded an average temperature of 52.3°F, which is 0.6 degrees above average, while Walla Walla's average monthly temperature of 51.8°F was 0.4 degrees above average.


Notable April Events
  • April 5th: The temperature at Pullman dropped to 27 degrees.
  • April 13th: The wind at Royal City North gusted to 39 mph.
  • April 13th: 1.11 inches of rain fell at Long Beach.
  • April 14th: The high temperature at Garfield East was only 45 degrees.
  • April 15th: The low temperature at Ritzville plunged to 23 degrees.
  • April 17th: The temperature at Desert Aire rose to 80 degrees.
  • April 20th: The temperature at Azwell soared to 83 degrees.
  • April 26th: The temperature at Ritzville plummeted to 22 degrees.
  • April 27th: The temperature at Vancouver soared to 81 degrees.

April Temperature Extremes (°F)
  Observed in 2015 Record Monthly Extremes
Site (Period of Record) Warmest Date Coldest Date Warmest Date Coldest Date
Prosser (WSU IAREC; 1989-2015)
81.5
4/28/2015
30.7
4/4/2015
87.2
4/23/2012
25.3
4/1/2008
Moxee (1989-2015)
79.5
4/21/2015
21.7
4/4/2015
88.2
4/23/2012
14.8
4/21/2008
Mt. Vernon (WSU NWREC; 1994-2015)
70.8
4/27/2015
34.6
4/5/2015
79.5
4/11/2004
25.4
4/1/2008
Wenatchee (WSU TFREC; 1994-2015)
80.3
4/20/2015
29.3
4/5/2015
87.6
4/23/2012
23.5
4/3/2007
Tri-Cities (1995-2015)
84.7
4/28/2015
30.9
4/5/2015
91.7
4/30/1998
25.0
4/1/2008
Walla Walla (1992-2015)
82.0
4/28/2015
32.0
4/5/2015
85.0
4/29/1998
25.9
4/1/2008
Moses Lake (1989-2015)
81.0
4/28/2015
28.2
4/5/2015
87.6
4/30/1998
20.5
4/1/2008
Omak (Pogue Flat; 2005-2015)
78.4
4/28/2015
30.6
4/4/2015
85.5
4/23/2012
25.2
4/1/2008
Royal City East (2008-2015)
80.1
4/28/2015
32.1
4/5/2015
85.5
4/23/2012
27.7
4/1/2008
Pullman (2008-2015)
79.1
4/28/2015
26.3
4/16/2015
80.5
4/22/2012
20.0
4/19/2011
Long Beach (WSU Long Beach; 2005-2015)
75.5
4/27/2015
31.8
4/9/2015
87.6
4/30/2014
28.0
4/2/2008
Sequim (2008-2015)
69.3
4/20/2015
31.1
4/4/2015
72.0
4/30/2014
22.5
4/4/2009
Seattle (2011-2015)
77.6
4/27/2015
36.0
4/5/2015
NA
NA
NA
NA
Vancouver (WSU RE; 2008-2015)
81.5
4/27/2015
31.5
4/15/2015
82.4
4/30/2014
25.5
4/4/2009

Agriculture Report
Cherries and apples were already at or near bloom in south central Washington as of the beginning of April (AWN). Chelan County was about 10 days ahead of normal, while asparagus harvest commenced in Yakima County. Dryland winter wheat was in fair to good condition, but more precipitation was needed. As of early April, Douglas County Extension reported straw breaker foot rot in winter wheat.

As of mid April, less rain and warmer weather in western Washington created ideal fieldwork conditions. Dry conditions continued to be a concern east of the Cascades, and frost protection was needed on several nights. Isolated cold damage was reported in Douglas and Chelan Counties. The winter wheat crop also showed signs of cold stress. Otherwise, crop development continued to be ahead of normal, and fruit tree thinning began in the Lower Yakima Valley (National Agricultural Statistics Service).

April 1 to April 30 Accumulated Growing Degree Days
  Base Temperature (°F)
32 43 50
Location 2015 5 Year Avg Difference 2015 5 Year Avg Difference 2015 5 Year Avg Difference
Prosser (WSU IAREC)
589
549
40
260
226
34
85
76
9
Tri-Cities
650
622
28
323
293
30
129
116
13
Walla Walla
597
554
43
271
229
42
90
73
17
Wenatchee (WSU TFREC)
598
554
44
269
230
39
102
78
24
Moxee
487
477
10
166
166
0
46
50
-4
Omak (Pogue Flat)
553
509
44
224
188
36
82
58
24
Moses Lake
578
549
29
248
226
22
77
74
3
Pullman
393
364
29
93
90
3
18
24
-6
Royal City East
595
562
33
266
235
31
94
82
12
Mt. Vernon (WSU NWREC)
533
493
40
203
168
35
37
28
9
Long Beach (WSU Long Beach)
472
456
16
143
131
12
24
15
9
Sequim
464
420
44
134
104
30
19
10
9

GDD are calculated by subtracting a base temperature from the average daily temperature (°F). If the resulting value is less than 0, then it is set to 0. Thus GDD are always 0 or greater.

GDD = (Tmax+Tmin)/2 - Tbase


This Month in History
On April 30th, 2014, the temperature at Long Beach soared to a monthly record high of 88 degrees.

Climate Outlook
According to the Climate Prediction Center, above average temperatures are likely during May, especially in western areas of Washington, along with near average rainfall in the east and below average rainfall in the west. The signal for above average temperatures in Washington generally continues for the next 12 months. The odds are tilted toward below average precipitation for the mid-summer 2015 to early 2016 time period. El Niño conditions will likely persist and strengthen later in 2015.

Washington State University