2002 Weather Report

Erik B. G. Feibert and Clinton C. Shock

Malheur Experiment Station

Oregon State University

Ontario, OR

Introduction

Air temperature and precipitation have been recorded daily at the Malheur Experiment Station since July 20, 1942. Installation of additional equipment in 1948 allowed for evaporation and wind measurements. A soil thermometer at 4-inch depth was added in 1967. A biophenometer, to monitor degree days, and pyranometers, to monitor total solar and photosynthetically active radiation, were added in 1985.

Since 1962, the Malheur Experiment Station has participated in the Cooperative Weather Station system of the National Weather Service. The daily readings from the station are reported to the National Weather Service forecast office in Boise, Idaho.

On June 1, 1992, in cooperation with the U.S. Department of the Interior, Bureau of Reclamation, a fully automated weather station, connected by satellite to the Northwest Cooperative Agricultural Weather Network (AgriMet) computer in Boise, Idaho, began transmitting data from Malheur Experiment Station. The automated station continually monitors air temperature, relative humidity, dew point temperature, precipitation, wind run, wind speed, wind direction, solar radiation, and soil temperature at 8-inch and 20-inch depths. Data is transmitted via satellite to the Boise computer every 4 hours and is used to calculate daily Malheur County crop water-use estimates. The AgriMet database can be accessed through the internet at www.pn.usbr.gov/agrimet and is linked to the Malheur Experiment Station web page at www.cropinfo.net.

Starting in June 1997, the daily weather data and the monthly weather summaries have been posted on the Malheur Experiment Station web site on the internet at www.cropinfo.net.

Methods

The ground under and around the weather stations had been bare, but was covered with turfgrass on October 17, 1997. The grass is irrigated with subsurface drip irrigation. The weather data is recorded each day at 8:00 a.m. and consequently, in the tables of daily observations, refers to the previous 24 hours.

Evaporation is measured from April through October as inches of water evaporated from a standard 10-inch-deep by 4-ft-diameter pan over 24 hours. Evapotranspiration (Et) for each crop is calculated by the AgriMet computer using data from the AgriMet weather station and the Kimberly-Penman equation (Wright 1982). Reference Et is calculated for a theoretical 12- to 20-inch-tall crop of alfalfa assuming full cover for the whole season. Alfalfa mean Et is calculated for an alfalfa crop assuming a 15 percent reduction to account for cuttings. Evapotranspiration for all crops is calculated using the reference Et and factors for each crop that vary during the season depending on the degree of cover.

Wind run is measured as total wind movement in miles over 24 hours at 24 inches above the ground. Weather data averages in the tables refer to the years preceding and up to, but not including, the current year.

2002 Weather

The total precipitation for 2002 (6.18 inches) was lower than the 10-year and 59-year averages and was the third lowest since 1943 (Table 1). Precipitation was lowest in 1949 (5.16 inches) followed by 1966 (5.74 inches). Precipitation for all months except December was lower than the 10-year and 59-year averages. Precipitation for May was 9 percent of the 59-year average.

The highest temperature for the year was 107°F on July 12 and 14, close to the record of 108°F on August 4, 1961 (Table 10). The lowest temperature for the year was 10°F on February 5. Average monthly air temperatures for June, July, and December were substantially higher than the 10-year and 59-year averages (Table 2). A heat wave starting on July 11 resulted in 4 consecutive days with maximum air temperatures above 100°F (July 11 - 102°F, July 12 -107°F, July 13 - 106°F, and July 14 - 107°F). The heat wave coincided with particularly susceptible stages of development for many local crops (period of high rates of onion bulb growth, tuber bulking, and grain ripening).

The months of June and July had more growing degree days (50° to 86°F) than the 16-year average (Table 3). The other months accumulated fewer or close to the same number of growing degree days as the 16-year average. The total number of growing degree days in 2002 was close to the 10-year average, especially when compared to the highest (1994) and lowest (1993) years for growing degree days since 1990 (Fig. 1). June and July had substantially more and August had substantially fewer degree days in the above-optimal range (86° to 104°F) than the previous 10-year average (Table 4). The total number of degree days in the above optimal range in 2002 was close to the previous 10-year average.

January had a total wind run 40 percent higher than the 10-year average (Table 5). The months of September and November had total wind runs 3 and 46 percent lower, respectively, than the 10-year average. December had a total wind run 28 percent higher than the 10-year average. Total pan-evaporation for April through July was higher than the 10-year and 54-year averages (Table 6). Total pan evaporation for August and September was lower than the 10-year and 54-year averages. Total pan-evaporation for 2002 was close to the 10-year average, but higher than the 54-year average. Total Et for all crops in 2002, except hybrid poplar, was slightly higher than the 10-year average (Table 7).

From February through November the average monthly maximum and minimum 4-inch soil temperatures were lower than the 10-year and 35-year averages (Table 8). The difference in soil temperature between 2002 and the averages is probably influenced by the installation of turf around the weather station in October of 1997.

The last spring frost ([32°F) occurred on May 8, 10 days later than the 26-year average date of April 28; the first fall frost occurred on October 12, 8 days later than the 26-year average date of October 4 (Table 9).

The weather in 2002 did not exceed any record weather events recorded over the 60-year history for the Malheur Experiment Station (Table 10).

Total snowfall for 2002 was the third lowest in the last 10 years (Table 11).

References

Wright, J.L. 1982. New evapotranspiration crop coefficients. J. Irrig. Drain. Div., ASCE 108:57-74.

Table 1. Monthly precipitation at the Malheur Experiment Station, Oregon State University, Ontario, OR, 1991-2002.

Year

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total

----------------------------------------------------- inches -----------------------------------------------------
1991 0.59 0.44 0.88 0.81 1.89 1.09 0.01 0.04 0.35 1.01 1.71 0.43 9.25
1992 0.58 1.36 0.25 0.74 0.21 1.43 0.36 0.01 0.09 0.95 1.15 1.51 8.64
1993 2.35 1.02 2.41 2.55 0.70 1.55 0.18 0.50 0.00 0.80 0.64 0.60 13.30
1994 1.20 0.57 0.05 1.02 1.62 0.07 0.19 0.00 0.15 1.23 2.46 1.49 10.05
1995 2.67 0.28 1.58 1.16 1.41 1.60 1.10 0.13 0.07 0.57 0.88 2.56 14.01
1996 0.97 0.86 1.03 1.19 2.39 0.12 0.32 0.31 0.59 0.97 1.18 2.76 12.69
1997 2.13 0.17 0.25 0.66 0.67 0.86 1.40 0.28 0.40 0.43 1.02 0.94 9.21
1998 2.26 1.45 0.95 1.43 4.55 0.36 1.06 0.00 1.00 0.04 1.07 1.11 15.28
1999 1.64 2.50 0.59 0.23 0.28 1.02 0.00 0.09 0.00 0.40 0.49 0.73 7.97
2000 2.01 2.14 0.97 0.72 0.28 0.26 0.03 0.06 0.39 1.74 0.38 0.66 9.64
2001 1.15 0.41 1.11 0.70 0.37 0.64 0.32 0.00 0.10 0.68 1.33 1.00 7.78
2002 0.77 0.27 0.49 0.77 0.09 0.60 0.14 0.10 0.36 0.29 0.44 1.86 6.18
10-yr avg 1.70 1.08 0.92 1.04 1.25 0.79 0.50 0.14 0.28 0.78 1.08 1.34 10.80
59-yr avg 1.36 0.98 0.95 0.80 1.05 0.78 0.26 0.39 0.49 0.71 1.17 1.31 10.27

Table 2. Monthly air temperature, Malheur Experiment Station, Oregon State University, Ontario, OR, 2002.


Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Max Min Max Min Max Min Max Min Max Min Max Min Max Min Max Min Max Min Max Min Max Min Max Min

----------------------------------------------------------------------oF ----------------------------------------------------------------
Max 49 38 57 35 67 44 75 53 87 62 99 70 107 73 98 64 94 58 77 54 66 39 57 45
Min 28 13 30 10 39 14 52 25 52 27 58 40 85 55 77 46 64 36 39 15 40 12 30 18
2002 avg 38 26 42 23 52 30 65 38 73 45 84 55 95 62 87 54 81 47 65 36 50 26 43 29
10-yr avg 37 24 45 27 56 32 64 37 74 46 80 51 90 57 91 54 81 46 66 36 47 28 37 23
59-yr avg 35 20 43 25 55 31 64 37 74 45 82 52 91 58 90 55 80 46 66 36 48 28 37 22

Figure 1. Cumulative growing degree days (50-86 deg F) over time, Malheur Experiment Station, Oregon State University, Ontario, OR.

Table 3. Monthly total growing degree days (50-86 deg F), Malheur Experiment Station, Oregon State University, Ontario, OR, 1991-2002.

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total
1991 0 13 16 124 212 389 776 718 436 194 1 0 2,879
1992 0 13 106 202 482 574 639 704 385 174 4 0 3,283
1993 0 0 23 81 423 358 464 524 408 252 6 0 2,539
1994 0 2 92 189 369 523 794 774 509 144 2 0 3,398
1995 0 29 32 106 293 433 680 588 472 101 3 10 2,747
1996 0 5 53 135 243 446 805 658 364 194 18 2 2,923
1997 4 0 81 117 419 509 661 706 481 157 20 0 3,154
1998 0 2 52 112 68 571 802 749 515 151 16 4 3,042
1999 0 2 43 72 329 459 683 703 416 184 30 0 2,921
2000 0 4 36 194 342 536 751 743 368 133 2 0 3,109
2001 0 0 63 126 401 488 715 761 472 155 27 0 3,208
2002 0 2 32 137 319 562 805 621 437 142 14 2 3,073

16-yr avg

0 7 54 155 319 508 715 681 432 169 12 1 3,053

Table 4. Monthly total degree days in the 86-104 deg F range, Malheur Experiment Station, Oregon State University, Ontario, OR, 1991-2001.

Year Apr May Jun Jul Aug Sep Oct Total
1991 0 0 2 41 36 4 0 83
1992 0 5 20 23 54 2 0 104
1993 0 4 4 2 11 5 0 26
1994 0 2 16 68 54 7 0 147
1995 0 0 4 23 22 7 0 56
1996 0 0 5 54 32 4 0 95
1997 0 4 0 27 31 5 0 67
1998 0 0 0 63 45 14 0 122
1999 0 1 2 21 16 1 0 41
2000 0 0 7 41 43 4 0 95
2001 0 5 7 25 45 4 0 86
2002 0 0 14 54 11 5 0 85
10-yr avg 0 1 7 40 37 6 0 87

Table 5. Wind-run daily totals and monthly totals, Malheur Experiment Station, Oregon State University, Ontario, OR, 2002.

Daily

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

------------------------------------------- miles -----------------------------------------------

Mean

68 73 83 83 71 58 44 53 36 48 29 72

Max.

181 176 225 213 140 143 103 111 112 157 151 267

Min.

10 35 33 21 14 14 17 11 7 6 4 3

Annual total

-------------------------------------------- miles ------------------------------------------------

2002

2,100 2,052 2,568 2,478 2,186 1,745 1,366 1,638 1,075 1,481 874 2,226

10-yr avg

1,500 1,745 2,355 2,455 2,362 2,002 1,817 1,697 1,635 1,783 1,643 1,743

54-yr avg




2,145 1,936 1,571 1,481 1,331 1,263 1,290

Table 6. Pan-evaporation totals, Malheur Experiment Station, Oregon State University, Ontario, OR, 2002.

Totals Apr May Jun Jul Aug Sep Oct Total
Daily -------------------------------------- inches ---------------------------------------
Mean 0.24 0.29 0.33 0.37 0.34 0.23 0.15
Max. 0.57 0.44 0.50 0.57 0.50 0.40 0.32
Min. 0.04 0.15 0.07 0.27 0.20 0.09 0.06
Annual ---------------------------------------- inches ------------------------------------
2002 6.84 8.99 10.03 11.56 10.54 6.93 4.50 59.39
10-yr avg 5.94 8.80 9.36 11.26 10.74 7.42 4.31 58.27
54-yr avg 5.58 7.69 8.88 11.12 9.62 6.29 3.22 51.78

Table 7. Total Et (acre-inches/acre), Malheur Experiment Station, Oregon State University, Ontario, OR, 1992-2002.

Year

Reference Et Alfalfa (mean) Winter grain Spring grain Sugar beet

Onion

Potato

Dry bean Field corn 1st year poplar 2nd year poplar 3rd year + poplar
1992 53.7 44.4 26.9 27.9 36.1 30.3 28.8 21.3 29.8 -- -- --
1993 51.9 36.4 21.3 22.7 29.3 24.1 22.8 17.9 23.7 -- -- --
1994 57.6 40.6 21.3 22.6 34.5 29.5 28.2 21.1 27.7 -- -- --
1995 49.6 37.1 18.9 22.2 29.0 26.7 23.6 16.7 23.7 -- -- --
1996 52.8 39.8 22.3 24.1 32.9 27.2 26.3 19.5 25.7 -- -- --
1997 55.2 41.5 23.8 25.3 33.4 28.0 26.6 19.7 25.1 -- -- --
1998 55.0 40.7 21.3 23.9 32.4 28.2 26.2 21.0 27.9 23.9 37.1 44.0
1999 58.6 43.9 25.0 26.4 33.7 28.9 26.5 21.7 28.5 24.3 37.8 45.5
2000 58.7 45.5 26.0 25.7 38.3 32.0 29.5 24.1 30.6 24.9 38.9 47.1
2001 57.9 43.8 25.5 27.2 34.8 30.3 27.4 21.4 29.1 23.7 37.0 44.7
2002 58.8 41.7 25.9 28.7 35.2 30.4 27.7 21.9 27.8 23.6 36.7 44.4
10-yr avg 55.1 41.4 23.2 24.8 33.4 28.5 26.6 20.4 27.2 24.2 37.7 45.3

Table 8. Monthly soil temperature at 4-inch depth, Malheur Experiment Station, Oregon State University, Ontario, OR 2002.


Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Max Min Max Min Max Min Max Min Max Min Max Min Max Min Max Min Max Min Max Min Max Min Max Min

-----------------------------------------------------------------oF ------------------------------------------------------------
Max 36 35 39 36 49 44 56 51 68 64 77 71 80 76 72 70 70 66 58 54 45 43 42 41
Min 31 31 30 30 33 30 45 41 51 47 58 55 71 64 66 61 58 54 44 40 37 34 35 33
2002 avg 34 33 33 32 40 37 51 46 59 54 69 63 75 69 69 64 65 61 53 49 41 39 37 36
10-yr avg 34 33 38 35 48 42 57 48 68 58 76 64 82 71 81 71 73 64 58 52 44 41 36 35
35-yr avg 33 32 38 34 50 41 61 48 73 58 81 66 89 74 87 73 76 64 61 51 44 39 34 33

Table 9. Last and first frost(32 deg F) dates and number of frost-free days, Malheur Experiment Station, Oregon State University, Ontario, OR, 1990-2002.

Year

Date of last frost Date of first frost Total frost-free days
Spring Fall
1990 May 8 Oct 7 152
1991 Apr 30 Oct 4 157
1992 Apr 24 Sep 14 143
1993 Apr 20 Oct 11 174
1994 Apr 15 Oct 6 174
1995 Apr 16 Sep 22 159
1996 May 6 Sep 23 140
1997 May 3 Oct 8 158
1998 Apr 18 Oct 17 182
1999 May 11 Sep 28 140
2000 May 12 Sep 24 135
2001 April 29 Oct 10 164
2002 May 8 October 12 157
1976-2001 Avg April 28 October 4 159

Table 10. Record weather events at the Malheur Experiment Station, Oregon State University, Ontario, OR, 1943-2002.

Record event Measurement Date

Greatest annual precipitation

16.87 inches 1983

Greatest monthly precipitation

4.55 inches May 1998

Greatest 24-hour precipitation

1.52 inches Sep 14, 1959

Greatest annual snowfall

40 inches 1955

Greatest 24-hour snowfall

10 inches Nov 30, 1975

Earliest snowfall

1 inch Oct 25, 1970

Highest air temperature

108°F Aug 4, 1961

Total days with maximum air temp. m100°F

17 days 1971

Lowest air temperature

-26°F Jan 21 and 22, 1962

Total days with minimum air temp. [0°F

35 days 1985

Lowest soil temperature at 4-inch depth

12°F Dec 24, 25, and 26, 1990

Table 11. Annual snowfall totals at the Malheur Experiment Station, Oregon State University, Ontario, OR, 1991-2002.

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 10-yr avg 59-yr avg
-------------------------------------------------- inches --------------------------------------------------
7.5 15.5 36.0 32.0 15.0 14.5 5.8 14.6 13.2 13.8 15.5 11.5 17.6 18.6