2003 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.

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. 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 are transmitted via satellite to the Boise computer every 4 hours and are used to calculate daily Malheur County crop water-use estimates. The AgriMet database can be accessed through the internet at http://www.usbr.gov/pn/agrimet/currentdata.html and is linked to the Malheur Experiment Station web page at www.cropinfo.net.

Methods

The ground under and around the weather stations was bare until October 17, 1997, when it was covered with turfgrass. The grass is irrigated with subsurface drip irrigation. The weather data are recorded each day at 8:00 a.m. Consequently, the data in the tables of daily observations refer 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.

2003 Weather


The total precipitation for 2003 (8.78 inches) was lower than the 10-year and 59-year averages (Table 1).

The highest temperature for the year was 110° F on July 22, higher than the record of 108° F on August 4, 1961 (Table 2). The lowest temperature for the year was 15° F occurring on various dates in February, November, and December. Average monthly maximum and minimum air temperatures for all months except April, May, and November were higher than the 10-year and 60-year averages (Table 2). July had 13 days with maximum air temperatures equal to or above 100°F.

The months of June, July, August, and October had 17, 18, 11, and 69 percent more growing degree days (50° to 86°F), respectively, than the 17-year average (Table 3). The total number of growing degree days in 2003 (3,443) was the second highest since measurements started being taken in 1986 (3,446 in 1988). Compared to 1994 (the second highest for growing degree days in the last 13 years) the growing degree days in 2003 accumulated more rapidly in July and then again in October (Fig. 1). In 1994 the growing degree days accumulated more evenly during the season. July had the highest number of degree days in the above-optimal range (86° to 104°F) since 1991 (Table 4). The total number of degree days in the above-optimal range in 2003 (130) was second to 1994 with 147.

The months of January, and April through October had total wind runs lower than the 10-year and 55-year averages (Table 5). Total pan-evaporation for June and July were 20 and 11 percent higher than the 10-year and 54-year averages (Table 6). Total Et for all crops in 2003 was higher than the 10-year average (Table 7).

From March through November the average monthly maximum and minimum 4-inch soil temperatures were lower than the 10-year and 35-year averages (Table 8). In January, February, and December the average monthly maximum and minimum 4-inch soil temperatures were higher than the 10-year and 35-year averages. The difference in soil temperature between 2003 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 19, 21 days later than the 27-year average date of April 28; the first fall frost occurred on October 11, 7 days later than the 27-year average date of October 4 (Table 9).

The maximum air temperature in 2003 was 110° F on July 22, surpassing the previous record of 108° F on August 4, 1961 (Table 10).

Total snowfall for 2003 (4.5 inches) was the lowest in the last 10 years and the lowest since 1943 (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, 1991-2003.

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
2003 1.46 0.48 0.99 1.12 1.52 0.24 0.36 0.11 0.15 0.02 0.86 1.47 8.78
10-yr avg 1.72 0.97 0.94 1.04 1.24 0.71 0.47 0.15 0.31 0.71 1.01 1.37 10.64
60-yr avg 1.35 0.96 0.95 0.80 1.03 0.78 0.26 0.38 0.49 0.70 1.16 1.32 10.19

Table 2. Monthly air temperature, Malheur Experiment Station, Oregon State University, Ontario, OR, 2003.


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 ----------------------------------------------------------------
Highest 49 40 58 40 74 50 75 50 98 64 98 64 110 73 101 74 94 59 87 65 73 45 57 40
Lowest 28 21 39 15 44 20 47 28 59 32 69 45 86 55 84 51 58 35 47 23 37 15 27 15
2003 avg 41 31 48 28 58 35 62 39 73 46 85 55 97 62 92 59 82 48 72 42 47 27 43 30
10-yr avg 37 24 44 26 55 31 64 37 73 46 80 51 91 58 90 54 81 47 66 36 48 28 38 24
59-yr avg 35 20 43 25 55 31 64 37 74 45 82 52 91 58 90 55 80 46 65 36 48 28 37 22



Figure 1. Cumulative growing degree days (50-86°F) over time for selected years compared to 13-year average, Malheur Experiment Station, Oregon State University, Ontario, OR.

Table 3. Monthly total growing degree days (50-86°F), Malheur Experiment Station, Oregon State University, Ontario, OR, 1991-2003.

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
2003 0 4 72 112 319 594 846 754 448 281 11 2 3,443

17-year avg

0 6 53 152 324 510 720 682 435 166 13 1 3,064

Table 4. Monthly total degree days in the above ideal 86 -104°F range, Malheur Experiment Station, Oregon State University, Ontario, OR, 1991-2003.

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
2003 0 5 9 74 36 5 0 130
13-yr avg 0 2 7 38 34 6 0 87

Table 5. Wind-run daily totals and monthly totals, Malheur Experiment Station, Oregon State University, Ontario, OR, 2003.

Daily

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

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

Mean

33 71 87 69 56 49 44 35 30 36 60 79

Max.

106 196 250 131 126 100 110 82 135 133 158 204

Min.

5 17 20 29 21 13 10 10 6 6 18 23

Annual total

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

2003

1,029 1,995 2,684 2,066 1,730 1,457 1,365 1,078 886 1,108 1,794 2,450

10-yr average

1,634 1,897 2,393 2,500 2,326 1,987 1,800 1,737 1,616 1,815 1,596 1,842

55-yr average




2,151 1,941 1,574 1,479 1,336 1,259 1,293


Table 6. Pan-evaporation totals, Malheur Experiment Station, Oregon State University, Ontario, OR, 2003.

Totals April May Jun Jul Aug Sep Oct Total
Daily -------------------------------------- inches ---------------------------------------
Mean 0.18 0.27 0.38 0.40 0.33 0.24 0.17
Max. 0.33 0.47 0.48 0.64 0.49 0.41 0.31
Min. 0.08 0.09 0.26 0.08 0.14 0.03 0.03
Annual ---------------------------------------- inches ------------------------------------
2003 5.51 8.22 11.30 12.48 10.09 7.21 5.30 60.11
10-yr avg 6.03 8.82 9.42 11.29 10.72 7.38 4.32 57.98
55-yr avg 5.61 7.71 8.90 11.13 9.64 6.30 3.24 52.53

Table 7. Total Et (acre-inches/acre), Malheur Experiment Station, Oregon State University, Ontario, OR, 1992-2003.

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
2003 54.2 44.1 27.5 31.7 39.1 32.0 32.4 22.5 29.6 24.3 37.9 45.9
10-year average 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, 2003.


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 ------------------------------------------------------------
Highest 40 39 43 42 49 46 57 51 85 65 75 67 79 73 76 71 72 68 65 62 46 43 44 43
Lowest 34 32 35 33 37 34 45 37 53 49 67 61 70 62 70 64 60 56 48 44 36 34 34 33
2002 avg 37 36 39 37 44 41 51 46 61 55 71 64 74 68 73 68 65 61 57 53 42 38 39 37
10-yr avg 33 32 38 35 49 41 59 49 69 58 77 65 84 72 82 72 74 65 60 52 44 41 35 34
35-yr avg 33 32 38 34 50 41 61 48 72 58 81 66 89 74 87 73 76 63 60 51 44 39 34 33

Table 9. Last and first frost ([32°F) dates and number of frost-free days, Malheur Experiment Station, Oregon State University, Ontario, OR, 1990-2003.

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 Apr 29 Oct 10 164
2002 May 8 Oct 12 157
2003 May 19 Oct 11 145
1976-2002 Avg April 28 October 4 159

Table 10. Record weather events at the Malheur Experiment Station, Oregon State University, Ontario, OR, 1943-2003.

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

110°F July 22, 2003

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, 1991-2003.

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 10-yr avg 60-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 4.5 17.2 18.5