AgWeatherNet 2019 Washington Weather Year in Review

Craig Oswald, Field Meteorologist, 509-786-9256
Joe Zagrodnik, Postdoctoral Research Associate

Overview
This review will be a recap of Washington State's 2019 weather and provide a look at some of the average and extreme weather conditions experienced this year and how they compare to climatology. There will also be a brief agriculture report included at the end highlighting some of the ag related weather statistics and general agriculture statistics from the year.

2019 Weather
Temperature:
The following tables illustrate the average monthly high and low temperatures from various regions across the state. This data was compiled from AgWeatherNet stations near the regions listed. While this is admittedly an intimidating conglomeration of numbers, the usual seasonal pattern of gradually warming and then cooling temps, as well as warmer to the south and cooler to the north mantra (warmer west of the Cascades in our case as well), can be readily seen. But there is one more thing that jumped out to us as well. Statewide, the month of February was much cooler than either January or March. As many may recall, a significant cold air intrusion occurred that month and spilled into the beginning of March.

This intrusion was enough to pull the monthly average minimum temperature for February down 8.3°F below normal as averaged statewide. And 6°F below the average minimum temperature for March as averaged statewide. Local climatology for monthly average minimum temperature can be found here, thanks to the NOAA Western Regional Climate Center.

The monthly average maximum temperature for February was down 10.9°F from normal as averaged statewide. And 4°F below the average maximum temperature for March as averaged statewide. Local climatology for monthly average maximum temperature can be found here. This intrusion will be touched upon further in a following section.

2019 Average Monthly Low Temperatures (°F)
Region Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Wenatchee
28
18
26
41
51
57
61
62
52
34
27
29
Omak
26
17
27
40
49
53
58
58
51
33
28
28
Tri-cities
32
19
26
46
51
57
60
62
55
37
28
31
Walla Walla
32
22
29
44
49
54
58
60
53
36
31
31
Pullman
28
17
20
39
43
46
46
49
45
31
28
30
Spokane
27
18
23
37
45
48
51
54
47
31
28
29
Moses Lake
28
17
26
40
47
50
55
58
49
34
28
28
Yakima
30
21
31
46
54
58
62
65
54
37
31
30
Mt. Vernon
34
26
33
42
47
50
54
54
52
40
35
37
Tacoma
33
27
31
41
46
49
54
55
52
37
35
37
Vancouver
34
31
32
42
48
51
56
56
53
37
35
36
2019 Average Monthly High Temperatures (°F)
Region Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Wenatchee
39
31
50
65
77
82
87
90
74
59
48
37
Omak
36
29
49
63
75
81
86
88
72
56
45
34
Tri-cities
42
33
49
67
78
84
88
91
77
61
48
41
Walla Walla
43
35
46
63
74
81
87
90
75
59
48
41
Pullman
38
31
43
56
68
73
80
83
69
52
46
39
Spokane
37
29
42
56
69
74
81
85
69
52
45
39
Moses Lake
38
30
46
62
74
79
83
86
73
56
45
36
Yakima
40
32
48
65
76
82
86
89
75
59
50
38
Mt. Vernon
50
40
55
58
67
69
73
75
67
56
51
47
Tacoma
50
42
57
60
70
73
76
78
70
59
51
47
Vancouver
49
42
56
61
70
74
78
80
70
60
54
47

After examining the above tables, it is interesting to also make a full year examination of average temperatures across the state. The map below is courtesy of NOAA's Western Regional Climate Center and illustrates the entire year of 2019's average temperature departure from the 30 year, 1981-2010, average temperature. At a glance the map indicates a close to average year aside from two distinct pockets of cooler than average temperatures located over the Horse Heaven hills/eastern Yakima Valley and northern Stevens County regions. The heavy black dashed line placed upon the map roughly represents the central Cascades and the divide between 'western' and 'eastern' Washington and will be carried through in subsequent maps. Close examination reveals that western Washington experienced a slightly warmer year in 2019, while eastern Washington experienced a slightly cooler year than climatology.

2019 Ave Temperature Dep From Ave

To break this down another step further, the first of the following two maps illustrates the entire year of 2019's average minimum temperature departure from the 30 year 1981-2010 average minimum temperature. The second map illustrates the same except that it represents the average maximum temperature (both also courtesy of NOAA's Western Regional Climate Center). It can be seen from the minimum temperature map that much of the state was near the 30 year average. However, an area of interest indicating where minimum temperatures, which are usually achieved just before sunrise each day, were cooler in 2019 is the Upper Chehalis Basin in western Lewis county. It's surroundings, the Olympic Peninsula and greater Seattle area, indicate slightly warmer minimum temperatures. The western Yakima Valley and western part of the Basin also indicate a larger geographical area where minimum temperatures were slightly warmer than compared to climatology.

2019 Ave Temperature Dep From Min

Examination of the second map (please note the scale change compared to the first of these two maps) indicates cooler than average maximum day time high temperatures over, most notably, the Horse Heaven Hills and eastern Yakima valley region. As noted in the total average temperature map, the cool anomaly here looks to be attributed to cooler maximum temperatures during 2019. And eastern Washington in general maintained a cooler than average high temperature. Nearly all of western Washington experienced warmer than average high temperatures with again a notable exception being the Upper Chehalis Basin which clung to slightly cooler high temperatures as well.

A major reason for the warmer temperatures relative to average in western Washington compared with eastern Washington was anomalously warm offshore sea surface temperatures, especially during summer and autumn. During periods with onshore flow, surface air temperatures in regions west of the Cascades are influenced by the warmer ocean temperatures. The mountains prevent this influence from reaching east of the Cascades.

Both average minimum and average maximum temperature maps seem to indicate a rather variable year across much of north central/northeastern Washington. Perhaps due to the complex terrain features, valley areas may have maintained slightly cooler temperatures longer on average, especially during the cold air outbreak, as cold air pooled in these areas without much option for escape. While upland areas perhaps maintained slightly warmer temperatures than average due to the lower than average snow year last winter (this is illustrated by the first figure in the next section titled 'Precipitation', with Washington state outlined in the heavy black box. Courtesy NWS Pendleton). This would generally result in an earlier snow melt in upland areas greatly decreasing surface albedo and allowing spring time solar radiation to more readily warm these areas.

2019 Ave Temperature Dep From Max

Precipitation:

The following graphic illustrates the seasonal precipitation from the previous winter season (2018-2019). Washington state is highlighted by the heavy black box. The main takeaway here is the lack of winter precipitation, usually in the form of snow, across northern Washington and the Cascades, as well as rain in western Washington. (image courtesy of NWS Pendleton). The lack of snow pack in general can have implications for low land spring run off and has been a large contributor to the drought observed through parts of Washington since May 2018 (Drought.gov).

2019 Seasonal Precipitation

The following table displays the monthly precipitation totals from various regions across the state with the year total listed on the far right of the table. This data was again compiled from AgWeatherNet stations within the regions listed. The map below the table (courtesy of NOAA's Western Regional Climate Center) is a graphical display of 2019 year total precipitation throughout the state. As expected, the Cascades and Olympics have the highest accumulations due to their orographic effects, with eastern Washington being significantly drier due to its residency within the rain shadow of the Cascades.

2019 Monthly Precip Totals (inches)
Region Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year Total
Wenatchee
1.2
1.2
0.4
0.5
0.9
0.8
0
0.6
1.6
0.7
0.2
1.3
11
Omak
1.1
0.2
0.6
0.6
2.4
0.1
0.2
0.2
2.3
0.2
0.3
0.9
9.1
Tri-cities
1.2
0.9
0.4
0.5
0.3
0.1
0
0.1
0.6
0.2
0.1
0.3
4.7
Walla Walla
2.3
2.6
1.2
3
1.9
0.4
0
0.3
1.3
1.5
0.6
1.1
16.2
Pullman
1.4
1.4
0.3
2.7
1
0.7
0
0.3
0.6
1.7
0.4
1.4
11.9
Spokane
1.4
2.1
0.5
1.7
1.8
0.6
0.3
0.8
1.5
1.1
0.6
1.7
14.1
Moses Lake
1.1
0.4
0.3
1
0.2
0.3
0.6
0.2
0.3
0.7
0.2
0.7
6
Yakima
1.2
0.6
0.4
0.4
0.6
0
0
0.4
0.4
0.5
0
0.5
5
Mt. Vernon
1.8
2.3
1.4
2.5
0.9
1.4
0.8
0.9
5.2
4.2
2.1
3.5
27
Tacoma
3.1
4.8
1.4
3.1
0.8
0.6
1
1.2
3.4
3.6
1.8
6.4
31.2
Vancouver
3
4.6
1.4
3.3
1.6
0.6
1
0.6
4.1
1.8
1.6
5
28.6
2019 Total Precipitation

But how does the 2019 year total precipitation compare to climatology? The map below, again courtesy of NOAA's Western Regional Climate Center, displays the 2019 departure as compared to the 30 year (1981-2010) average. Nearly the entire state was short of precipitation in 2019, helping to explain the May 2019 drought conditions briefly mentioned earlier.

Fortunately, the summertime months were relatively cool and wet, especially in western Washington. After a brief spell of warm weather in mid-June, the remainder of the summer was free of prolonged heat waves. Additionally, most of western Washington received several inches of rain in July and August which helped to suppress wildfires and prevent drought conditions from worsening. After a dry start to the water year in October and November, dry conditions in the Cascades and western Washington have recently abated according to Drought.gov, no doubt at the hand of some of the record setting rainfall western Washington has received as well as the heavy snowfall totals through the Cascades.

Total Precipitation Departure From Average

The following map depicts regions in which drought was declared by the Washington state Department of Ecology last spring. A quick comparison with the previous map shows a strong correlation between drought conditions and lack of precipitation as expected. Again, current drought conditions for Washington state can be found here.

May 20, 2019 Drought Declaration Areas
Notable Weather Events and Extremes:

The following table illustrates the extreme monthly high and low temperatures, 24 hour precipitation (as measured midnight to midnight), and maximum wind gust from various regions across the state. This data was again compiled from AgWeatherNet stations within the regions listed.

2019 Monthly Precip Totals (inches)
Region Minimum Temp (°F) Maximum Temp (°F) 24hr Precip (inches) (12:00AM-12:00AM) Max wind Gust (mph)
Wenatchee
2 (4 Mar)
103 (7 Aug)
0.84 (10 Sept)
25 (9 Apr)
Omak
5 (7 Feb)
102 (7 Aug)
1.27 (16 May)
29 (8 Aug)
Tri-cities
0 (7 Feb)
103 (7 Aug)
0.33 (20 Jan)
37 (28 Oct)
Walla Walla
6 (5 Mar)
103 (6 Aug)
0.95 (17 May)
28 (1 Jul)
Pullman
-12 (4 March)
96 (7 Aug)
1.08 (19 Oct)
42 (27 Apr)
Spokane
-4 (7 Feb)
98 (7 Aug)
0.93 (17 May)
43 (23 Jul)
Moses Lake
7 (1 Mar)
100 (7 Aug)
0.54 (19 Oct)
41 (27 Nov)
Yakima
6 (7 Feb)
101 (7 Aug)
0.46 (18 Jan)
34 (25 Mar)
Mt. Vernon
9 (10 Feb)
85 (12 Jun)
2.01 (21 Oct)
35 (6 Jan)
Tacoma
12 (10 Feb)
92 (12 Jun)
1.77 (20 Dec)
23 (6 Jan & 11 Mar)
Vancouver
19 (6 & 7 Feb)
96 (27 Aug)
1.49 (18 Sept)
36 (5 Jan)

As alluded to earlier, one of the most memorable weather events of 2019 was the cold air and snow outbreak of February/early March. This prolonged cold air intrusion was due mainly to a stratospheric warming event that allowed the polar vortex to become split, weaken the jet stream, and meander into more southerly latitudes. The brunt of the arctic air was felt throughout the upper Midwest, however, this arctic intrusion also managed to impact parts of the western U.S. and Canada.

The more noteworthy weather phenomena associated during the roughly month-long cold air intrusion include substantial low land snow events throughout the state. The February 8-9 blizzard managed to shut down many highways and pass routes throughout the state due to large accumulations and drifting snow. Wind gusts of up to 80 mph were recorded at some locales. The Yakima Valley suffered a loss of approximately 1800 dairy cows killed by the storm, a loss of about $3.2 million according to the Washington State Dairy Federation. The Hanford site recorded 25.3" of snow which is a record since record keeping began here in 1945, surpassing the record of 22.7" for February set in 1950 (NWS Pendleton). Spokane experienced its second snowiest February on record at 29.8", with the top record being 39.6" measured in February 1893 (NWS Spokane).

No part of Washington escaped the wintery conditions, including lowland parts of western Washington that are unaccustomed to significant snowfall. Snow totals for the month of February show that Seattle recorded 20.2" of snow at Sea-Tac which makes it the snowiest February on record and 4th snowiest month recorded in the 75-year record at Sea-Tac (NOAA National Centers for Environmental Information, National Climate Report – Annual 2019). Other areas around Puget Sound and the surrounding regions received 3-4+ feet of snow including the foothills near Sequim and North Bend. The heavy snow not only disrupted travel but also caused widespread power outages from falling tree branches.

After a quick temperature recovery through the remainder of March, the rest of the spring and summer turned out near average weather wise. A stretch of hot weather at the beginning of August is notable for eastern Washington, but this doesn't quite come within range of record-breaking high temperatures. Also, summertime thunderstorm activity managed to create a few cases of localized flooding, but nothing on a large scale.

Autumn was relatively benign for the most part, but one notable period for eastern Washington in particular was a stretch of rain, snow showers, and unseasonably cold weather from late-September through mid-October that disrupted the fall harvest. One of the most unusual events from this period was 3.3" of snow that fell in Spokane on September 28-29, making 2019 the snowiest September on record in Spokane and the first September snowfall recorded since 1926. A number of record cold temperatures were also set on September 29th at Pullman, Wenatchee, Spokane, and Omak. Otherwise, a drier than normal autumn was also observed throughout Washington with few major weather events. Seattle only recorded 1.71" of rain in November, making it the driest November since 1976.

The next truly noteworthy weather event that took place was the prolonged rainfall experienced on the western side of the state due to an atmospheric river. Sea-Tac recorded 3.25" of rain on December 20, making it the 5th wettest day on record, with 5.02" received on October 20th 2003 holding the number one spot with records since 1945. The Chehalis, Skykomish, and the South Fork Stillaguamish rivers all had flood warnings issued with minor to moderate flooding forecasted. There were also several mudslides throughout the area, notably the Des Moines and Tacoma areas where a mudslide even covered an Amtrak line near Tacoma (NWS Seattle).

Agriculture Report
Growing Degree Days:
The following tables illustrate the number of base 50 growing degree days (GDD) accumulated through 2019. This data was again compiled from AgWeatherNet stations within the regions listed and calculated via the AgWeatherNet webpage. Even with the cold weather experienced in February and the beginning of March, growing degree days for the year 2019 fell very near average for base 50 GDD.
Number of Base 50 GDD in 2019 vs 10 year Average (2009-2018)
Region 2019 Average
Wenatchee
3109
3052
Omak
2749
2756
Tri-cities
3420
3354
Walla Walla
2990
3021
Pullman
1645
1686
Spokane
1962
1989
Moses Lake
2460
2579
Yakima
3342
3470
Mt. Vernon
1732
1712
Tacoma
1984
2034
Vancouver
2217
2292

As seen in the example graph taken from the Tri-cities region (Pasco), base 50 GDD were arguably slightly below average through the month of March, but as seen, quickly recovered through April and May. This put the region 166 GDD ahead of the average by the middle of June. From mid-June and on, base 50 GDD accumulated slightly slower and closer to the average rate with degree days floating either just above or just below the average through the end of the season in most cases.

Pasco Base 50 Growing Degree Days

The following map, courtesy of NOAA's Western Regional Climate Center, provides an overview of year 2019 accumulated base 50 GDD across Washington State.

2019 Growing Degree Days

The next table presented represents the number of base 40 growing degree days (GDD) accumulated through 2019 within the regions indicated. Like previous, this data was gathered and processed through the AgWeatherNet webpage. Compared to base 50, base 40 growing degree days appear to be slightly less than average in all regions.

Number of Base 40 GDD in 2019 vs 10 year Average (2009-2018)
Region 2019 Average
Wenatchee
5242
5331
Omak
4810
4916
Tri-cities
5669
5890
Walla Walla
5248
5561
Pullman
3513
3681
Spokane
3828
3976
Moses Lake
4520
4809
Yakima
5618
5928
Mt. Vernon
4210
4342
Tacoma
4458
4679
Vancouver
4695
4924

The next table presented represents the number of base 40 growing degree days (GDD) accumulated through 2019 within the regions indicated. Like previous, this data was gathered and processed through the AgWeatherNet webpage. Compared to base 50, base 40 growing degree days appear to be slightly less than average in all regions.

Pasco Base 40 Growing Degree Days

The following map, again courtesy of NOAA's Western Regional Climate Center, provides an overview of base 40 GDD across Washington State.

Base 40 Growing Degree Days

If a general statement had to be made, one might characterize the 2019 growing season as a little shorter than usual. The season got off to a late start, followed by a quick recovery through late spring and tracking near average over the summer. Then a slightly earlier end of the season was apparent through the beginning of autumn.

Ag Totals:

Lastly, a table is presented summing the 2019 total production of some of the main agricultural products for the state of Washington. The data available at the time of this writing is marginal since we are just beyond 2019, but worthwhile conclusions can still be inferred where the data set is not complete. More data will be added to the USDA National Agricultural Statistics Service for the year 2019 in the coming months. This information can be found following the link here. Data pertaining to crops not presented in the brief table below can also be found on the USDA site by following the previous link.

N2019 Washington Ag Summary
Product Production Price Yield Total Revenue
Apples
7,200,000,000/lbs
0.4 $/lb (Avg Jan-Jul)
N/A
$2.88 Billion
Milk
60,562,500/Cwt
18.72 $/Cwt (Avg Jan-Nov)
N/A
$1.13 Billion
Cattle
N/A
N/A
N/A
N/A
Potatoes
103,125,000/Cwt
N/A
625 Cwt/acre
N/A
Wheat (total)
142,735,000/BU
5.52 $/BU (Avg Jan-Nov)
64.7 BU/acre
$788 Million
Wheat (winter)
119,000,000/BU
5.47 $/BU (Avg Jan-Nov)
70 BU/acre
$651 Million
Grapes (total)
450,000/tons
N/A
N/A
N/A
Grapes (wine)
260,000/tons
N/A
N/A
N/A
Cherries (sweet)
500,000,000/lbs
N/A
N/A
N/A
Cherries (tart)
23,500,000/lbs
N/A
N/A
N/A
Hay & Haylage (total)
2,694,000/tons (dry basis)
N/A
4.02 tons/acre (dry basis)
N/A
Hay & Haylage (Alfalfa)
1,619,000/tons (dry basis)
N/A
4.63 tons/acre (dry basis)
N/A

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