2001 Pendleton, Oregon (PDT)

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2001 PENDLETON, OREGON (PDT)

Pendleton is located in the southeastern part of the Columbia Basin, that low country of northern Oregon and central and eastern Washington which is almost entirely surrounded by mountains. This Basin is bounded on the south by the high country of central Oregon, on the north by the mountains of western Canada, on the west by the Cascade Range and on the east by the Blue Mountains and the north Idaho plateau. The gorge in the Cascades through which the Columbia River reaches the Pacific is the most important break in the barriers surrounding this basin. These physical features have important influences on the general climate of Pendleton and the surrounding territory.

The Weather Service Office at Pendleton Airport is located in rolling country which slopes generally upward toward the Blue Mountains about 15 miles to the east and southeast. The Columbia River approaches the area from the northwest to its junction with the Walla Walla River at an elevation of 35l feet and some 25 miles north of Pendleton, then turns southwestward to be joined a few miles below by the Umatilla River. Both the Walla Walla and Umatilla Rivers have their sources in the Blue Mountains and flow westward to the Columbia. The observation station is at an elevation of nearly 1,500 feet, about 3 miles northwest of downtown Pendleton. The city of Pendleton lies in the shallow east–west valley of the Umatilla River, approximately 400 feet lower than the airport.

Precipitation in the Pendleton area is definitely seasonal in occurrence with an average of only 10 percent of the annual total occurring in the three–month period, July–September. Most precipitation reaching this area accompanies cyclonic storms moving in from the Pacific Ocean. These storms reach their greatest intensity and frequency from October through April. The Cascade Range west of the Columbia Basin reduces the amount of precipitation received from the Pacific cyclonic storms. This influence is felt, particularly, in the desert area of the central part of the Basin. A gradual rise in elevation from the Columbia River to the foothills of the Blue Mountains again results in increased precipitation. This increase supplies sufficient moisture for productive wheat, pea, and stock raising activity in the area surrounding Pendleton.

The lighter summertime precipitation usually accompanies thunderstorms which often move into the area from the south or southwest. On occasion, these storms are quite intense, causing flash flooding with resultant heavy property damage and even loss of life.

Seasonal temperature extremes are usually quite moderate for the latitude. The last occurrence in spring of temperatures as low as 32 degrees is mid–April, and the average last occurrence in the fall of 32 degrees is late October. At the city station, where cool air settles in the valley on still nights, temperatures of 32 degrees have been recorded later in the spring and earlier in the fall. Under usual atmospheric conditions, air from the Pacific, with moderate temperature characteristics, moves across the Cascades or through the Columbia Gorge resulting in mild temperatures in the Pendleton area. When this flow of air from the west is impeded by slow–moving high pressure systems over the interior of the continent, temperature conditions sometimes become rather severe, hot in summer and cold in winter. During the summer or early fall, if a stagnant high predominates to the north or east of Pendleton, the hot, dry conditions may prove detrimental to crops during late May and June, and cause fire danger in the forest and grassland areas during late summer and early fall. During winter, coldest temperatures occur when air from a cold high pressure system in central Canada moves southwestward across the Rockies and flows down into the Columbia Basin. Under this condition the heavy cold air sometimes remains at low levels in the Basin for several days while warmer air from the Pacific flows above it, causing comparatively mild temperatures at higher elevations. Extreme winter temperatures are not particularly common in the Pendleton area. Below zero readings are recorded in approximately 60 percent of winters. Maximum temperatures usually reach 100 degrees or slightly higher on a few days during the summer.

NORMALS, MEANS, AND EXTREMES

PENDLETON, OR (PDT)

LATITUDE:    LONGITUDE:    ELEVATION (FT):    TIME ZONE:    WBAN: 24155

45 41′ 54″ N  118 50′ 03″ W  GRND:  1504  BARO:  1504  PACIFIC (UTC + 8)

ELEMENTPORJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECYEAR
TEMPERATURE FNORMAL DAILY MAXIMUM3039.746.954.261.370.079.587.886.276.363.748.940.562.9
MEAN DAILY MAXIMUM5439.546.353.761.570.178.587.785.976.963.448.940.962.8
HIGHEST DAILY MAXIMUM6670757991100108110113102928067113
YEAR OF OCCURRENCE199519961964197719861961193919611955198019991980AUG 1961
MEAN OF EXTREME MAXS.5458.462.268.177.788.094.6101.499.792.479.965.959.379.0
NORMAL DAILY MINIMUM3027.231.635.439.445.852.958.057.749.941.034.127.941.7
MEAN DAILY MINIMUM5426.731.034.839.546.052.457.957.350.241.033.728.541.6
LOWEST DAILY MINIMUM66-22-18118253542403011-12-19-22
YEAR OF OCCURRENCE195719501993193619541991197119802000193519851983JAN 1957
MEAN OF EXTREME MINS.547.315.023.830.135.142.447.947.438.728.920.811.829.1
NORMAL DRY BULB3033.539.244.850.357.966.272.972.063.152.441.534.352.3
MEAN DRY BULB5433.038.644.250.558.065.572.871.663.652.341.334.652.2
MEAN WET BULB1831.934.239.744.249.353.656.956.351.744.337.628.844.0
MEAN DEW POINT1828.129.533.336.440.943.344.043.340.736.333.125.636.2
NORMAL NO. DAYS WITH:
MAXIMUM 90300.00.00.0*0.85.314.411.72.60.10.00.034.9
MAXIMUM 32308.62.70.20.00.00.00.00.00.00.02.18.121.7
MINIMUM 323020.114.58.83.20.10.00.00.00.23.110.819.780.5
MINIMUM 0301.40.40.00.00.00.00.00.00.00.00.11.23.1
H/CNORMAL HEATING DEG. DAYS309777226264412267115231453917059525294
NORMAL COOLING DEG. DAYS300000610726024088000701
RHNORMAL (PERCENT)3077736358524636384759747858
HOUR 04 LST3079787371686353536170788069
HOUR 10 LST3077716052474133364254727855
HOUR 16 LST3073634942373123263244687647
HOUR 22 LST3079766862564937405164778062
SPERCENT POSSIBLE SUNSHINE
W/OMEAN NO. DAYS WITH:
HEAVY FOG(VISBY 1/4 MI)647.44.91.90.30.20.10.00.00.21.06.18.430.5
THUNDERSTORMS640.00.00.20.91.82.02.02.11.20.30.10.010.6
CLOUDINESSMEAN:
SUNRISE-SUNSET (OKTAS)16.43.2
MIDNIGHT-MIDNIGHT (OKTAS)13.2
MEAN NO. DAYS WITH:
CLEAR11.03.04.05.07.0
PARTLY CLOUDY13.02.05.03.0
CLOUDY13.02.09.010.03.0
PRMEAN STATION PRESSURE(IN)2828.5228.4728.4028.4228.4028.3928.4028.3928.4428.4928.4728.5428.44
MEAN SEA-LEVEL PRES. (IN)1830.1330.1030.0230.0129.9629.9629.9629.9529.9830.0630.0930.1930.03
WINDSMEAN SPEED (MPH)377.27.98.89.59.29.18.88.48.07.57.77.58.3
PREVAIL. DIR (TENS OF DEGS)2314142626262626271414151626
MAXIMUM 2-MINUTE:
SPEED (MPH)647495548434140434544415455
DIR. (TENS OF DEGS)24152525242527232724262225
YEAR OF OCCURRENCE200019991997199719961998200019971999200120001998MAR 1997
MAXIMUM 5-SECOND:
SPEED (MPH)656586355515147595352486666
DIR. (TENS OF DEGS)23162521242527232724262222
YEAR OF OCCURRENCE200019991997199819961998200019971999200120001998DEC 1998
PRECIPITATIONNORMAL (IN)301.511.141.161.040.990.640.350.530.590.861.581.6312.02
MAXIMUM MONTHLY (IN)663.923.032.822.783.182.701.452.582.342.793.764.684.68
YEAR OF OCCURRENCE197019401983197819911947199319771941194719731973DEC 1973
MINIMUM MONTHLY (IN)660.210.070.240.010.030.03T0.00TT0.040.210.00
YEAR OF OCCURRENCE194919641941195619641986196719691993198719391989AUG 1969
MAXIMUM IN 24 HOURS (IN)661.291.411.331.241.521.491.192.191.231.881.351.252.19
YEAR OF OCCURRENCE195619941983199019721947194819931981198219711978AUG 1993
NORMAL NO. DAYS WITH:
PRECIPITATION 0.013012.010.910.68.77.25.82.93.64.76.111.712.296.4
PRECIPITATION 1.0030*0.0*0.1*0.00.0*****0.1
SNOWFALLNORMAL (IN)306.12.11.00.1T0.00.00.00.00.22.25.216.9
MAXIMUM MONTHLY (IN)6441.616.84.92.2TTT0.00.03.214.926.641.6
YEAR OF OCCURRENCE1950199419711975199319941993197319851983JAN 1950
MAXIMUM IN 24 HOURS (IN)6413.316.14.02.2TTT0.00.03.28.09.916.1
YEAR OF OCCURRENCE1950199419701975199319941993197319771948FEB 1994
MAXIMUM SNOW DEPTH (IN)5216126000000281116
YEAR OF OCCURRENCE195719941993197119781985JAN 1957
NORMAL NO. DAYS WITH:
SNOWFALL 1.0302.20.60.40.10.00.00.00.00.00.10.61.95.9
PRECIPITATION (inches) 2001 PENDLETON, OR (PDT)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
19720.961.081.470.681.970.800.580.360.160.580.702.3111.65
19730.501.090.430.270.670.150.010.081.341.713.764.6814.69
19740.791.570.812.130.260.190.90TT0.291.001.599.53
19753.531.300.650.970.300.280.730.670.001.800.841.9813.05
19761.771.001.651.090.920.330.161.770.180.540.190.4410.04
19770.480.641.510.181.870.370.062.581.170.512.002.4213.79
19782.821.601.032.780.630.760.772.210.92T2.371.8617.75
19791.431.721.181.170.390.210.091.400.301.681.830.6212.02
19802.481.391.600.592.141.120.770.030.591.220.841.2013.97
19810.891.351.431.201.591.530.940.031.310.861.912.3115.35
19821.540.771.220.840.310.630.510.241.472.670.342.2012.74
19830.861.572.820.700.731.440.520.560.460.841.673.4215.59
19840.531.741.831.701.021.130.060.440.391.022.140.9212.92
19850.441.331.130.370.440.690.340.262.100.892.111.2711.37
19861.662.581.130.431.180.030.480.021.280.802.120.8212.53
19871.480.641.390.470.850.380.340.050.03T0.761.237.62
19881.860.120.952.471.560.310.01T0.310.102.160.3710.22
19891.861.361.721.571.470.570.091.250.120.841.270.2112.33
19900.770.281.141.541.830.580.180.62T0.780.870.849.43
19910.980.571.000.713.182.140.240.42T0.922.680.6713.51
19920.411.040.261.210.070.940.700.430.421.321.150.738.68
19931.790.801.491.851.510.711.452.19T0.220.930.9213.86
19941.571.710.560.452.550.770.38T0.361.281.980.8512.46
19952.531.071.932.280.972.300.240.290.551.212.181.7317.28
19961.881.801.001.082.000.470.060.050.611.221.962.3214.45
19971.840.391.161.560.330.760.660.070.771.431.641.0511.66
19982.611.191.011.281.530.760.68T1.110.602.311.3714.45
19990.811.220.740.501.270.51T0.540.011.511.231.019.35
20001.992.982.420.691.600.720.07T2.012.061.220.5716.33
20010.950.621.311.890.451.120.520.080.091.541.150.7010.42
POR=102 YRS1.571.311.241.081.150.960.310.400.621.041.511.5012.69
AVERAGE TEMPERATURE (F) 2001 PENDLETON, OR (PDT)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
197234.037.447.847.660.968.374.776.261.151.142.627.152.4
197331.338.445.850.361.366.975.371.764.052.842.641.553.5
197430.443.846.451.757.371.173.375.567.554.844.840.654.8
197537.139.045.247.559.365.878.470.167.054.342.340.553.9
197639.237.942.850.258.863.773.467.767.353.142.735.952.7
197726.341.544.255.355.169.170.374.958.550.038.334.851.5
197832.239.345.748.054.466.372.269.460.551.733.529.550.2
197915.337.746.050.459.566.672.870.665.554.334.738.251.0
198025.636.141.351.956.460.472.166.963.351.342.039.250.5
198136.238.945.750.456.061.669.274.363.850.644.237.252.3
198235.038.143.547.656.867.671.171.560.750.737.335.751.3
198340.843.847.849.058.962.768.472.758.952.545.923.252.1
198434.639.746.848.254.762.172.972.260.449.141.830.451.1
198526.333.543.253.158.565.677.468.157.050.326.519.548.3
198635.939.048.850.058.670.067.675.858.954.042.231.552.7
198730.439.146.453.959.767.268.970.666.254.142.632.752.7
198832.441.144.151.956.863.972.070.063.458.444.333.952.7
198938.325.142.552.955.965.970.368.863.651.844.633.251.1
199039.637.945.754.856.464.775.272.268.251.345.425.853.1
199131.244.742.649.653.959.671.573.364.951.641.236.951.8
199238.742.447.752.862.470.471.972.661.954.239.832.053.9
199325.128.241.950.361.862.965.468.064.354.634.635.649.4
199441.034.946.754.460.164.475.371.767.251.640.435.353.6
199534.941.745.349.057.762.172.067.466.050.246.134.552.2
199634.435.743.352.054.564.074.772.161.051.140.335.451.5
199732.638.645.448.659.863.170.473.164.951.442.734.952.1
199837.942.945.950.356.265.477.474.667.850.945.536.254.3
199941.042.343.447.354.163.770.072.562.550.846.038.152.6
200035.539.244.154.058.365.971.670.761.649.735.131.151.4
200132.735.544.447.358.762.170.573.266.251.242.236.651.7
POR=96 YRS32.838.044.951.358.465.573.171.463.252.541.435.152.3

REFERENCE NOTES:

PAGE 1:

THE TEMPERATURE GRAPH SHOWS NORMAL MAXIMUM AND NORMAL MINIMUM DAILY TEMPERATURES (SOLID CURVES) AND THE ACTUAL DAILY HIGH AND LOW TEMPERATURES (VERTICAL BARS).

PAGE 2 AND 3:

H/C INDICATES HEATING AND COOLING DEGREE DAYS.

RH INDICATES RELATIVE HUMIDITY

W/O INDICATES WEATHER AND OBSTRUCTIONS

S INDICATES SUNSHINE.

PR INDICATES PRESSURE.

CLOUDINESS ON PAGE 3 IS THE SUM OF THE CEILOMETER AND SATELLITE DATA NOT TO EXCEED EIGHT EIGHTHS (OKTAS).

GENERAL:

T INDICATES TRACE PRECIPITATION, AN AMOUNT GREATER THAN ZERO BUT LESS THAN THE LOWEST REPORTABLE VALUE.

+ INDICATES THE VALUE ALSO OCCURS ON EARLIER DATES.

BLANK ENTRIES DENOTE MISSING OR UNREPORTED DATA.

NORMALS ARE 30–YEAR AVERAGES (1961–1990).

ASOS INDICATES AUTOMATED SURFACE OBSERVING SYSTEM.

PM INDICATES THE LAST DAY OF THE PREVIOUS MONTH.

POR (PERIOD OF RECORD) BEGINS WITH THE JANUARY DATA MONTH AND IS THE NUMBER OF YEARS USED TO COMPUTE THE MEAN. INDIVIDUAL MONTHS WITHIN THE POR MAY BE MISSING.

WHEN THE POR FOR A NORMAL IS LESS THAN 30 YEARS, THE NORMAL IS PROVISIONAL AND IS BASED ON THE NUMBER OF YEARS INDICATED.

0.* OR * INDICATES THE VALUE OR MEAN–DAYS–WITH IS BETWEEN 0.00 AND 0.05.

CLOUDINESS FOR ASOS STATIONS DIFFERS FROM THE NON–ASOS OBSERVATION TAKEN BY A HUMAN OBSERVER. ASOS STATION CLOUDINESS IS BASED ON TIME–AVERAGED CEILOMETER DATA FOR CLOUDS AT OR BELOW 12,000 FEET AND ON SATELLITE DATA FOR CLOUDS ABOVE 12,000 FEET.

THE NUMBER OF DAYS WITH CLEAR, PARTLY CLOUDY, AND CLOUDY CONDITIONS FOR ASOS STATIONS IS THE SUM OF THE CEILOMETER AND SATELLITE DATA FOR THE SUNRISE TO SUNSET PERIOD.

GENERAL CONTINUED:

CLEAR INDICATES 0–2 OKTAS, PARTLY CLOUDY INDICATES 3–6 OKTAS, AND CLOUDY INDICATES 7 OR 8 OKTAS. WHEN AT LEAST ONE OF THE ELEMENTS (CEILOMETER OR SATELLITE) IS MISSING, THE DAILY CLOUDINESS IS NOT COMPUTED.

WIND DIRECTION IS RECORDED IN TENS OF DEGREES (2 DIGITS) CLOCKWISE FROM TRUE NORTH. "00" INDICATES CALM. "36" INDICATES TRUE NORTH.

RESULTANT WIND IS THE VECTOR AVERAGE OF THE SPEED AND DIRECTION.

AVERAGE TEMPERATURE IS THE SUM OF THE MEAN DAILY MAXIMUM AND MINIMUM TEMPERATURE DIVIDED BY 2.

SNOWFALL DATA COMPRISE ALL FORMS OF FROZEN PRECIPITATION, INCLUDING HAIL.

A HEATING (COOLING) DEGREE DAY IS THE DIFFERENCE BETWEEN THE AVERAGE DAILY TEMPERATURE AND 65 F.

DRY BULB IS THE TEMPERATURE OF THE AMBIENT AIR.

DEW POINT IS THE TEMPERATURE TO WHICH THE AIR MUST BE COOLED TO ACHIEVE 100 PERCENT RELATIVE HUMIDITY.

WET BULB IS THE TEMPERATURE THE AIR WOULD HAVE IF THE MOISTURE CONTENT WAS INCREASED TO 100 PERCENT RELATIVE HUMIDITY.

ON JULY 1, 1996, THE NATIONAL WEATHER SERVICE BEGAN USING THE "METAR" OBSERVATION CODE THAT WAS ALREADY EMPLOYED BY MOST OTHER NATIONS OF THE WORLD. THE MOST NOTICEABLE DIFFERENCE IN THIS ANNUAL PUBLICATION WILL BE THE CHANGE IN UNITS FROM TENTHS TO EIGHTS (OKTAS) FOR REPORTING THE AMOUNT OF SKY COVER.

HEATING DEGREE DAYS (base 65 F) 2001 PENDLETON, OR (PDT)
YEARJULAUGSEPOCTNOVDECJANFEBMARAPRMAYJUNTOTAL
1972-735416542266311701036738588434169735467
1973-74116973726667211064589573391241294760
1974-758039313600750857721609517194574665
1975-7601243332673751791782679436206894794
1976-77442313636608961192653639299301265106
1977-7820352004617929271011714593504322465625
1978-7974114640393610941533757582432184626177
1979-801204332690282312108297283882671415669
1980-81433884386817948867245934352751265077
1981-82201128440617855919747662515256725232
1982-83227171435825901741588528470242955025
1983-8442118038156912929357295584963161345633
1984-854018249069210651196876665351224655810
1985-8642224245211491402898722497446277256136
1986-8733021333567510311065717571332201715244
1987-8825126533466899510046896373872641265206
1988-892241202086169578211113691354279425227
1989-90111776403607978781752591299262894866
1990-9191311419583121110395646894543381625492
1991-924252418707865810649527362127364559
1992-931128129333752101512311025709432153985916
1993-942735114318908903736838559321174835016
1994-95150304067319159286446024732371265107
1995-9612651452560941938840664387321645245
1996-9784153423733909998733599488185845317
1997-9813073415662927832611585442273374870
1998-9903564295788877386286625223361084947
1999-001720117433565830905740640324219574867
2000-0171213746889210469958196315232381215889
2001-14548419676874
COOLING DEGREE DAYS (base 65 F) 2001 PENDLETON, OR (PDT)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
197200005013431435855000911
197300006313732723272000831
197400009219272332122400958
197500002788423179109800834
197600002053270129103300578
197700016315219034816000725
1978000019323618216000528
197900002111426118665300650
19800002513232101442000417
19810004228155297101000587
19820000715821921547000646
1983000060321552466000499
1984000075525623151300603
1985000028913941277000647
198600028818412134135100772
1987000841145152194108400652
19880000169824616478900611
1989000057618214341000447
19900000492330245114300788
199100000821426756900554
199200015220422927545400810
1993000059424713699400387
199400082972341214103000767
19950000174423010889000488
1996000004231223039000623
19970000313419125879500598
19980006556390309144000910
1999000077818026050050580
20000000178921519640000557
20010000484319326593000642
SNOWFALL (inches) 2001 PENDLETON, OR (PDT)
YEARJULAUGSEPOCTNOVDECJANFEBMARAPRMAYJUNTOTAL
1972-730.00.00.0TT12.62.25.9T0.10.00.020.8
1973-740.00.00.03.29.15.32.60.5TT0.00.020.7
1974-750.00.00.00.0TT16.63.3T2.2T0.022.1
1975-760.00.00.00.05.23.00.30.30.10.00.00.08.9
1976-770.00.00.00.00.01.03.10.50.40.00.00.05.0
1977-780.00.00.00.08.511.56.1T3.90.0T0.030.0
1978-790.00.00.00.09.07.414.72.2T0.00.00.033.3
1979-800.00.00.00.04.3T16.60.93.90.00.00.025.7
1980-810.00.00.00.02.02.73.61.20.00.00.00.09.5
1981-820.00.00.00.00.65.15.71.51.9T0.00.014.8
1982-830.00.00.00.0T1.60.20.90.00.00.00.02.7
1983-840.00.00.00.0T26.61.01.2TT0.00.028.8
1984-850.00.00.00.0T6.20.812.70.6T0.00.020.3
1985-860.00.00.00.014.99.1T7.60.00.0T0.031.6
1986-870.00.00.00.01.26.85.80.0T0.00.00.013.8
1987-880.00.00.00.00.32.310.60.01.50.00.00.014.7
1988-890.00.00.00.0TT4.34.94.00.0T0.013.2
1989-900.00.00.00.00.01.0T2.01.30.00.00.04.3
1990-910.00.00.00.0T6.41.60.00.6T0.00.08.6
1991-920.00.00.02.31.0T0.8T0.00.00.00.04.1
1992-930.00.00.00.00.27.625.114.81.8TT0.049.5
1993-94T0.00.00.00.70.4T16.80.20.00.0T18.1
1994-950.00.00.00.00.63.82.07.2T0.00.00.013.6
1995-960.00.00.00.0
1996-9710.13.2T
1997-984.20.0
1998-990.00.00.80.02.4TTT0.0
1999-000.00.00.00.00.00.55.74.51.00.0T0.011.7
2000-010.00.00.00.00.72.53.10.5TTTT6.8
2001-0.00.00.00.0T3.0
POR=63 YRST0.00.00.11.73.86.73.60.90.1TT16.9

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