1997 WEATHER REPORT

Erik B. G. Feibert and Clint C. Shock
Malheur Experiment Station
Oregon State University
Ontario, Oregon

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Introduction and Methods

Daily observations of air temperature and precipitation have been recorded at the Malheur Experiment Station since July 20, 1942. Installation of additional equipment in 1948 allowed for evaporation and wind measurements. Evaporation is measured as inches of water evaporated from a standard 10-inch deep by 47.5-inch diameter pan over 24 hours. Wind run is measured as total wind movement in miles over a 24 hour period measured at 24 inches above ground level. A soil thermometer at 4-inch depth was added in 1967. A biophenometer, to monitor degree days, and pyranometers, to monitor solar and photosynthetically active radiation, were added in 1985.

Since 1962, daily readings from the station have been reported to the U.S. Department of Commerce, Environmental Science Service Administration, and the National Weather Service. Each day the 8 AM air temperature, preceding 24-hour air and soil temperature extremes, and 24-hour accumulated precipitation are recorded and were transmitted to radio station KSRV in Ontario. KSRV then conveyed this information, along with their own daily readings, to the U.S. Weather Station in Boise, Idaho. Duringthe irrigation season (April -October), evaporation, wind, and water temperature are also monitored and reported.

On June 1, 1992, in cooperation with the U.S. 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 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. Stored 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 database may be accessed via computer modem or through the Internet (http://www.pn.usbr.gov/agrimet).

In July 1997, the daily weather data started being reported directly to the National Weather Service computer via phone. In June 1997, the daily weather data and the monthly weather summaries started being posted on the Malheur Experiment Station web site on the Internet (http://www.primenet.com/mesosu). On October 17, 1997, sod was layed around and under the weather stations. The sod will be irrigated with subsurface drip irrigation. The ground around and under the weather stations prior to October 17, 1997, was bare.

1997 Weather

The most unusual weather events in 1997 were a tornado and a microburst. The tornado occurred on April 30 at approximately 11 AM and went through the station, but did not hit any buildings on the station. A minisprinkler system with risers attached to metal stakes that was being used to germinate an onion field was torn apart. Some of the risers with metal stakes were thrown into an adjacent field about 150 feet away. The tornado then proceeded into Ontario causing damage to some buildings. The microburst occurred on June 17 near Nyssa and Adrian, Oregon and caused extensive crop damage.

The weather in 1996 did not exceed any record weather events recorded over the 54-year history for the Malheur Experiment Station (Table 1). Total precipitation was 9.45 inches for the year, close to the 10-year and 54-year station averages (Table 2).

Total snowfall for 1996 was 5.8 inches, 29 and 30 percent below the 10-year and 54-year means, respectively (Table 3).

Mean monthly maximum air temperatures were close to the 10-year and 54-year means (Table 4). The monthly total accumulated growing degree days (50-86 oF) was slightly higher than the 10-year mean (Table 5, Figure 1). The monthly total number of degree days in the 86-104 oF range was close to the 8-year average (Table 6). The mean monthly maximum and minimum 4-inch soil temperatures were close to the 10- year and 54-year means (Table 7).

Total pan-evaporation for April through October was 59.8 inches, close to the 10-year mean and above the 48-year mean (Table 8).

The last spring frost (<32 °F) occurred on May 3, seven days later than the 20-year mean date of April 26; the first fall frost occurred on October 8, four days later than normal (Table 9).

The monthly wind-run totals for the months of April through October were higher than the 49-year mean (Table 10).
 

Table 1. Record weather events at the Malheur Experiment Station, Oregon State University, Ontario, Oregon.
Record event Measurement Date
Greatest annual precipitation 16.87 in 1983
Greatest 24-hour precipitation 1.52 in Sep 14, 1959
Greatest annual snowfall 40 in 1955
Greatest 24-hour snowfall 10 in Nov 30, 1975
Earliest snowfall 1 in Oct 25, 1970
Highest air temperature 108 oF Aug 4, 1961

 

Table 2. Annual precipitation. Malheur Experiment Station, Oregon State University, Ontario, Oregon, 1986-1997.
1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 10-yr mean 54-yr mean
--------------------------------------------- inches ---------------------------------------------
8.64 9.81 7.58 9.15 7.21 9.25 8.64 13.3 10.05 14.01 12.69 9.45 9.76 10.24

 

Table 3. Annual snowfall totals at the Malheur Experiment Station, Oregon State University, Ontario, Oregon, 1986-1997. 
1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 10-yr mean 54-yr mean
--------------------------------------------- inches ---------------------------------------------
13 15.5 34.8 25.1 5.7 7.5 15.5 36 32 15 14.5 5.8 20.01 19.62

 

Table 4. Monthly air temperature. Malheur Experiment Station, Oregon State University, Ontario, Oregon, 1997. 
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
  Daily
  High Low High Low High Low High Low High Low High Low High Low High Low High Low High Low High Low High Low
  ---------------------------------------------------- oF ----------------------------------------------
Max. 58 41 56 32 79 45 76 48 92 59 90 57 102 65 101 59 94 60 94 45 64 39 48 33
Min. 27 6 32 19 45 22 50 19 58 26 71 42 72 44 84 46 67 35 50 21 39 16 30 18
1997 mean 40 22 46 25 59 29 63 34 78 45 82 51 88 55 91 53 82 47 66 33 52 27 38 23
10-yr mean 35 20 43 23 56 31 65 38 74 46 82 53 90 57 89 54 81 46 67 35 47 27 38 20
53-yr mean 35 19 43 25 55 31 64 37 74 45 82 52 91 57 90 55 80 46 65 36 48 28 37 22

 

Table 5. Cumulative monthly growing degree-days (50-86 oF). Malheur Experiment Station, Oregon State University, Ontario, Oregon, 1988-1997.
Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1988 0 5 56 236 554 1,139 2,050 2,741 3,117 3,426 3,446 3,446
1989 0 0 13 197 469 1,018 1,751 2,332 2,721 2,838 2,852 2,852
1990 2 9 88 327 588 1,085 1,819 2,454 3,039 3,077 3,077 3,077
1991 0 13 29 153 365 754 1,530 2,248 2,684 2,878 2,879 2,879
1992 0 13 119 321 803 1,377 2,016 2,720 3,105 3,279 3,283 3,283
1993 0 0 23 104 527 885 1,349 1,873 2,281 2,533 2,539 2,539
1994 0 2 94 283 652 1,175 1,969 2,743 3,252 3,396 3,398 3,398
1995 0 29 61 167 460 893 1,573 2,161 2,633 2,734 2,737 2,747
1996 0 5 58 193 436 929 1,687 2,345 2,709 2,903 2,921 2,923
1997 4 4 85 202 621 1,130 1,791 2,497 2,977 3,134 3,154 3,154
Mean 1 8 63 218 548 1,034 1,754 2,411 2,852 3,020 3,029 3,030

 

Table 6. Monthly degree-days (86-104 oF). Malheur Experiment Station, Oregon State University, Ontario, Oregon, 1990-1997 
Year Apr May Jun Jul Aug Sep Oct
1990 0 0 13 56 41 14 0
1991 0 0 2 41 36 4 0
1992 0 5 20 23 54 2 0
1993 0 4 4 2 11 5 0
1994 0 2 16 68 54 7 0
1995 0 0 4 23 22 7 0
1996 0 0 5 54 32 4 0
1997 0 4 0 27 31 5 0
mean 0 2 8 37 35 6 0

 

Table 7. Monthly 4 inch soil temperature. Malheur Experiment Station, Oregon State University, Ontario, Oregon, 1997. 
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
  Daily
  High low High low High low High low High low High low High low High low High low High low High low High low
  ------------------------------------------------------ oF ------------------------------------------------
Max. 47 44 50 40 65 51 75 56 89 71 90 73 95 80 95 80 85 77 72 67 53 53 47 45
Min. 31 29 32 32 39 35 53 41 59 47 72 61 62 61 80 72 67 62 52 51 45 44 37 37
1997 mean 35 34 38 33 52 41 62 47 71 56 85 67 92 75 89 72 77 62 63 52 48 40 36 34
10-yr mean 33 32 39 35 51 42 62 50 73 59 81 67 89 74 87 74 78 66 63 53 45 40 35 33
31-yr mean 33 32 38 34 51 41 62 48 74 58 82 67 90 75 88 74 77 64 61 51 44 39 34 33

 

Table 8. Pan-evaporation totals. Malheur Experiment Station, Oregon State University, Ontario, Oregon, 1997. 
Totals April May Jun Jul Aug Sep Oct Total
Daily  -------------------------------------- inches ---------------------------------------
Mean 0.21 0.28 0.35 0.36 0.35 0.24 0.17  
Max. 0.35 0.5 0.47 0.55 0.55 0.39 0.46  
Min. 0.01 0.07 0.16 0.06 0.18 0.09 0.04  
Annual  ----------------------------------------- inches --------------------------------------
1997  6.17 8.66 10.43 11.06 10.82 7.32 5.38 59.84
10-yr mean 6.1 9.01 9.81 11.83 10.42 7.59 4.36 59.12
48-yr mean 5.54 7.6 8.8 11.1 9.5 6.19 3.09 51.15

 

Table 9. Last and first frost (<32 °F) dates and number of frost-free days. Malheur Experiment Station, Oregon State University, Ontario, Oregon, 1976-1997.
Year Date of last frost Date of first frost Total number of frost-free days
Spring Fall
1976 Apr 23 Oct 5 165
1977 Apr 20 Sep 22 155
1978 Apr 23 Oct 14 174
1979 Mar 20 Oct 27 221
1980 Apr 13 Oct 17 187
1981 Apr 14 Oct 1 170
1982 May 5 Oct 5 153
1983 Apr 27 Sep 20 146
1984 May 7 Sep 25 141
1985 May 13 Sep 30 140
1986 May 23 Oct 12 142
1987 Apr 21 Oct 11 173
1988 May 2 Oct 30 181
1989 May 19 Sep 13 117
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 23 139
1997 May 3 Oct 8 158
Mean April 26  October 4 161

 

Table 10. Daily wind-run totals and monthly totals, Malheur Experiment Station, Oregon State University, Ontario, OR, 1997.

Total Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Daily ---------------------------------- miles --------------------------------------
Max. 278 180 168 226 172 145 118 105 127 231 88 163
Min. 24 15 30 38 14 33 30 27 25 18 22 12
Mean 58 64 81 99 64 78 61 54 60 86 50 53
Annual ------------------------------------ miles ---------------------------------------
1997 1,787 1,792 2,513 2,970 1,981 2,331 1,877 1,686 1,808 2,668 1,491 1,594
10-yr mean        2,247 2,369 1,983 1,774 1,597 1,562 1,660    
49-yr mean        2,110 1,891 1,531 1,449 1,291 1,228 1,252