2001 Knoxville, Tennessee (TYS)

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2001 KNOXVILLE, TENNESSEE (TYS)

Knoxville is located in a broad valley between the Cumberland Mountains, which lie northwest of the city, and the Great Smoky Mountains, which lie southeast of the city. These two mountain ranges exercise a marked influence upon the climate of the valley. The Cumberland Mountains, to the northwest, serve to retard and weaken the force of the cold winter air which frequently penetrates far south of the latitude of Knoxville over the plains areas to the west of the mountains.

The mountains also serve to modify the hot summer winds which are common to the plains to the west. In addition, they serve as a fixed incline plane which lifts the warm, moist air flowing northward from the Gulf of Mexico and thereby increases the frequency of afternoon thunderstorms. Relief from extremely high temperatures which such thunderstorms produce serves to reduce the number of extremely warm days in the valley.

July is usually the warmest month of the year. The coldest weather usually occurs during the month of January. Sudden great temperature changes occur infrequently. This again is due mainly to the retarding effect of the mountains. Summer nights are nearly always comfortable.

Rainfall is ample for agricultural purposes and is favorably distributed during the year for most crops. Precipitation is greatest in the wintertime. Another peak period occurs during the late spring and summer months. The period of lowest rainfall occurs during the fall. A cumulative total of approximately 12 inches of snow falls annually. However, this usually comes in amounts of less than 4 inches at one time. It is unusual for snow to remain on the ground in measurable amounts longer than one week.

The topography also has a pronounced effect upon the prevailing wind direction. Daytime winds usually have a southwesterly component, while nighttime winds usually move from the northeast. The winds are relatively light and tornadoes are extremely rare.

NORMALS, MEANS, AND EXTREMES

KNOXVILLE, TN (TYS)

LATITUDE:    LONGITUDE:    ELEVATION (FT):    TIME ZONE:    WBAN: 13891

35 49′ 05″ N  83 59′ 09″ W  GRND:  979  BARO:  982  EASTERN (UTC + 5)

ELEMENTPORJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECYEAR
TEMPERATURE FNORMAL DAILY MAXIMUM3045.950.961.370.477.684.587.186.781.270.659.950.168.8
MEAN DAILY MAXIMUM5447.352.360.570.378.185.088.087.281.571.359.450.069.2
HIGHEST DAILY MAXIMUM607783869294102103102103918480103
YEAR OF OCCURRENCE195019961963194219621988195219441954195319481982SEP 1954
MEAN OF EXTREME MAXS.5467.270.978.585.088.192.894.994.191.683.475.968.582.6
NORMAL DAILY MINIMUM3026.029.136.644.653.161.866.065.359.046.037.530.046.2
MEAN DAILY MINIMUM5429.432.138.747.456.264.068.167.160.648.038.231.848.5
LOWEST DAILY MINIMUM60-24-81223243494936255-6-24
YEAR OF OCCURRENCE198519961980198719861956198819461967198719501983JAN 1985
MEAN OF EXTREME MINS.549.712.922.231.441.452.659.758.847.132.722.714.733.8
NORMAL DRY BULB3036.040.149.057.565.473.276.676.070.158.448.740.157.6
MEAN DRY BULB5438.342.349.658.967.274.478.177.271.159.548.841.058.9
MEAN WET BULB1835.038.744.151.860.967.767.166.260.453.545.037.652.3
MEAN DEW POINT1829.732.637.345.656.464.464.263.256.849.239.832.947.7
NORMAL NO. DAYS WITH:
MAXIMUM 90300.00.00.0*0.85.110.48.52.80.00.00.027.6
MAXIMUM 32303.51.30.10.00.00.00.00.00.00.00.11.46.4
MINIMUM 323020.816.58.61.8*0.00.00.00.01.07.617.774.0
MINIMUM 0300.5*0.00.00.00.00.00.00.00.00.00.10.6
H/CNORMAL HEATING DEG. DAYS3089969749623494000182384897723937
NORMAL COOLING DEG. DAYS30000910624636034117133001266
RHNORMAL (PERCENT)3072686563717476767673727372
HOUR 01 LST3077747172828687888785807881
HOUR 07 LST3081808081868890929289848285
HOUR 13 LST3063595451575861616056596459
HOUR 19 LST3066605652606265666765666863
SPERCENT POSSIBLE SUNSHINE5740475363646564636161494056
W/OMEAN NO. DAYS WITH:
HEAVY FOG(VISBY 1/4 MI)592.91.81.61.22.32.12.13.33.64.43.12.631.0
THUNDERSTORMS590.81.53.14.46.98.49.56.83.11.31.00.547.3
CLOUDINESSMEAN:
SUNRISE-SUNSET (OKTAS)14.03.2
MIDNIGHT-MIDNIGHT (OKTAS)13.2
MEAN NO. DAYS WITH:
CLEAR14.01.04.013.011.0
PARTLY CLOUDY11.03.05.0
CLOUDY12.03.010.04.04.0
PRMEAN STATION PRESSURE(IN)2929.1029.0029.0029.0028.9929.0029.0029.0029.0029.1029.1029.0929.03
MEAN SEA-LEVEL PRES. (IN)1830.1330.1130.0529.9930.0030.0130.0330.0230.0630.1030.1330.1530.07
WINDSMEAN SPEED (MPH)447.68.08.58.56.96.46.15.55.65.56.77.26.9
PREVAIL. DIR (TENS OF DEGS)2824242423232423230504242324
MAXIMUM 2-MINUTE:
SPEED (MPH)643394364403443382843493964
DIR. (TENS OF DEGS)27222428201524032626252528
YEAR OF OCCURRENCE199620001996199619991997199620002000200120001996APR 1996
MAXIMUM 5-SECOND:
SPEED (MPH)653484876525168483656615776
DIR. (TENS OF DEGS)22232527201425032326242827
YEAR OF OCCURRENCE199619981996199619991997199720002000200120001996APR 1996
PRECIPITATIONNORMAL (IN)304.174.065.093.724.133.974.673.133.072.843.754.5447.14
MAXIMUM MONTHLY (IN)6011.749.3811.8111.0710.988.2112.668.889.196.6710.3611.6312.66
YEAR OF OCCURRENCE195419441994199819741989199919421989194919481961JUL 1999
MINIMUM MONTHLY (IN)600.950.741.690.390.740.200.330.770.42T0.970.45T
YEAR OF OCCURRENCE198619681986197619701944199519541985196319421965OCT 1963
MAXIMUM IN 24 HOURS (IN)603.893.425.773.693.403.574.693.255.082.444.064.895.77
YEAR OF OCCURRENCE194619911994199819841972194219591944196119481969MAR 1994
NORMAL NO. DAYS WITH:
PRECIPITATION 0.013011.911.012.510.911.310.111.59.38.28.010.511.0126.2
PRECIPITATION 1.00300.70.91.40.71.01.01.40.70.80.80.71.211.3
SNOWFALLNORMAL (IN)305.43.91.30.70.00.00.00.00.0T0.21.913.4
MAXIMUM MONTHLY (IN)5915.123.320.210.7TT0.0T0.0T18.212.223.3
YEAR OF OCCURRENCE1962196019601987194519981995199319521963FEB 1960
MAXIMUM IN 24 HOURS (IN)5912.017.514.110.7TT0.0T0.0T18.28.918.2
YEAR OF OCCURRENCE1962196019931987194519981995199319521969NOV 1952
MAXIMUM SNOW DEPTH (IN)52101515700000010615
YEAR OF OCCURRENCE196619601993198719521963MAR 1993
NORMAL NO. DAYS WITH:
SNOWFALL 1.0301.71.20.60.10.00.00.00.00.00.00.10.64.3
PRECIPITATION (inches) 2001 KNOXVILLE, TN (TYS)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
19727.354.194.982.544.495.026.761.614.705.993.367.0258.01
19733.242.5910.245.155.715.264.382.313.283.485.017.3858.03
19747.055.246.155.7710.982.702.923.143.332.355.184.5259.33
19754.664.6810.422.432.982.432.251.613.284.022.923.5945.27
19763.862.185.220.395.533.463.751.982.875.333.454.4242.44
19772.551.526.086.961.166.491.085.786.914.045.063.3050.93
19785.221.014.424.103.445.275.062.441.260.823.625.9142.57
19796.184.174.214.307.213.809.472.292.641.975.731.9253.89
19805.541.788.723.303.801.943.572.342.381.533.781.7840.46
19811.053.622.834.843.025.532.033.486.094.153.014.1443.79
19826.034.886.363.265.523.936.602.682.682.665.214.8954.70
19831.582.901.995.885.423.263.183.890.953.344.405.6942.48
19842.264.423.793.3710.144.349.031.720.853.262.872.4948.54
19853.174.111.982.861.604.772.634.070.423.045.392.3636.40
19860.953.901.692.252.400.691.893.373.593.843.834.0832.48
19874.684.632.912.184.622.664.671.081.930.601.213.4934.66
19884.292.942.422.342.350.513.603.202.681.524.823.9934.66
19894.966.263.823.505.318.212.683.169.191.474.922.7456.22
19905.886.905.732.564.711.727.563.022.683.641.778.9955.16
19912.536.996.363.973.106.023.456.133.141.105.2410.2358.26
19923.873.363.992.113.203.074.624.221.773.054.296.6844.23
19934.092.206.162.503.780.902.036.044.772.253.337.0445.09
19947.088.8111.817.903.045.975.944.191.202.382.932.0263.27
19954.904.543.541.747.053.900.332.082.463.586.212.5042.83
19967.532.744.724.504.572.964.771.333.451.177.715.4450.89
19975.205.176.343.826.765.703.752.023.322.902.782.3750.13
19984.622.714.7511.073.847.965.692.071.311.422.515.9553.90
19996.623.504.853.404.925.5812.660.850.822.842.401.7050.14
20005.143.424.376.695.903.366.121.403.82T4.352.4547.02
20014.746.462.632.823.463.884.143.743.560.861.554.6642.50
POR=131 YRS4.634.555.124.123.904.064.483.542.802.563.404.3847.54
AVERAGE TEMPERATURE (F) 2001 KNOXVILLE, TN (TYS)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
197242.539.448.259.564.970.875.575.971.956.847.544.858.1
197338.039.955.856.463.574.876.776.273.862.452.441.159.3
197449.343.155.259.868.170.577.776.569.858.650.841.960.1
197543.345.546.657.570.174.677.678.868.960.150.241.159.5
197634.348.252.658.963.473.976.274.967.754.543.237.557.1
197727.241.455.062.969.875.380.378.974.057.452.640.259.6
197829.434.649.061.166.675.478.777.174.858.254.442.858.5
197933.036.753.159.966.972.875.077.672.258.351.442.258.3
198041.636.647.659.168.175.282.181.773.756.047.340.159.1
198133.441.946.863.563.977.181.478.370.258.949.438.758.6
198233.843.153.055.269.372.677.676.770.059.550.946.459.0
198338.041.149.753.265.472.578.579.670.360.247.436.457.7
198435.343.447.757.362.874.873.374.167.167.646.347.558.1
198529.437.150.258.665.772.576.575.168.563.756.834.857.4
198635.043.948.758.668.177.281.476.772.860.252.439.159.5
198736.842.249.255.071.375.578.579.670.152.850.243.558.7
198833.939.450.157.265.074.478.779.671.352.749.740.457.7
198942.841.353.557.862.473.377.576.870.959.448.132.258.0
199044.748.953.657.965.975.478.077.972.159.952.145.161.0
199141.243.852.062.872.074.979.376.571.461.047.143.560.5
199240.545.848.359.064.072.277.973.771.357.448.340.058.2
199343.539.545.756.267.076.083.078.770.657.948.440.258.9
199432.043.449.561.963.976.576.875.869.060.153.644.858.9
199539.240.753.161.067.373.880.281.570.558.643.637.158.9
199636.439.644.855.169.474.276.876.268.959.244.143.357.3
199739.446.654.254.062.271.978.475.771.758.943.939.258.0
199842.846.049.457.370.775.979.477.776.061.950.144.461.0
199943.644.145.361.266.275.078.677.769.958.552.742.459.6
200037.546.153.255.969.974.877.376.970.761.047.434.058.7
200135.545.846.361.768.472.978.077.568.256.954.245.659.3
POR=131 YRS38.941.849.458.767.274.777.876.871.359.748.440.658.8

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 KNOXVILLE, TN (TYS)
YEARJULAUGSEPOCTNOVDECJANFEBMARAPRMAYJUNTOTAL
1972-730092515226228286972832729703581
1973-74001013537373448160630419041102884
1974-750023215439713666542563257903427
1975-7600421724377339444853802039103487
1976-77001932065184511666583191103324123
1977-7800324237476410978464871487404035
1978-790002103106819857863761674603561
1979-800002204077007158155291853213604
1980-8100232845237619746415561049403960
1981-8200321964618099596063842952003762
1982-8300302284165778296624723565033623
1983-84005116352387891261953024013954060
1984-85004430556536109577645920851133768
1985-860044862509279225824992065103567
1986-870201973777978636314833131303676
1987-8800153704376609567344582476693952
1988-8900338445475568166036025814813704
1989-90013620449910116224433582396803481
1990-910026182382612730589405931603035
1991-92004615953866075354951222511363561
1992-9300132294947696597085922703823774
1993-94003723249576110165974731399303843
1994-9500111583366207946743641625403173
1995-9600222166388578777326223024504311
1996-97003019662366378651233233312483607
1997-9800122662579468152850023430123631
1998-990011334386326565786041492403215
1999-000028206359694846542354265963309
2000-0100341495229559085305711552513850
2001-0057263320594
COOLING DEGREE DAYS (base 65 F) 2001 KNOXVILLE, TN (TYS)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
197200053511933323472234201205
1973004195629836935528260201445
197400939142179399365171191701340
19750003917329339743416826001530
197603126482733563141075001133
1977051457188317483440283141001811
1978000371303194323843028001612
197900152011124231739922423401355
19800001613631553852529012001832
1981000626537351242119314101641
19820017615723339637218765281443
198300467123542546221723001443
19840001277306263290116120201186
198500112081247363322155531101263
19860002115637451737324155601743
1987000182153214274601720001613
198800319742974314582009001491
19890210477625739537421935001415
199001133210131641040624532101557
19910093223930645336424442621697
199200049912304102792060001265
19930001010633956643221221301689
1994000546734937234213715001336
19950035013426848052119226101675
19960401018728537135315222301387
199701594422242333820946001297
19980024821234645440233843011828
1999000416730442940318113001438
2000000216730939037621133401492
20010006213724741139316019101430
SNOWFALL (inches) 2001 KNOXVILLE, TN (TYS)
YEARJULAUGSEPOCTNOVDECJANFEBMARAPRMAYJUNTOTAL
1972-730.00.00.00.0TT9.0T1.9T0.00.010.9
1973-740.00.00.00.00.02.0TT1.80.00.00.03.8
1974-750.00.00.00.0T1.61.3T2.50.00.00.05.4
1975-760.00.00.00.0TT0.32.80.00.00.00.03.1
1976-770.00.00.00.01.02.17.90.20.00.00.00.011.2
1977-780.00.00.00.00.10.611.35.51.80.00.00.019.3
1978-790.00.00.00.00.0T4.718.4T0.00.00.023.1
1979-800.00.00.00.0TT0.511.03.5T0.00.015.0
1980-810.00.00.00.0TT5.02.5T0.00.00.07.5
1981-820.00.00.00.0T0.14.40.11.1T0.00.05.7
1982-830.00.00.00.00.03.01.13.40.72.00.00.010.2
1983-840.00.00.00.00.00.72.83.5T0.00.00.07.0
1984-850.00.00.00.00.0T14.28.30.00.00.00.022.5
1985-860.00.00.00.00.00.43.65.0T0.00.00.09.0
1986-870.00.00.00.0TT7.5T1.610.70.00.019.8
1987-880.00.00.00.0TT9.20.9T0.00.00.010.1
1988-890.00.00.00.0T2.61.82.80.00.00.00.07.2
1989-900.00.00.0TT1.1TTT0.00.00.01.1
1990-910.00.00.00.00.0TT1.20.7T0.00.01.9
1991-920.00.00.00.00.2TT0.0TT0.00.00.2
1992-930.00.00.00.00.00.3T1.015.1T0.00.016.4
1993-940.00.00.0T0.00.33.3T0.60.00.00.04.2
1994-950.00.00.00.00.00.02.01.10.60.00.00.03.7
1995-960.0T0.00.0T10.0
1996-971.5
1997-98T3.30.40.1T0.0TT
1998-990.00.00.00.00.0TT2.12.00.0T0.04.1
1999-000.00.00.00.00.0T2.0TT0.0T0.02.0
2000-01
2001-
POR=55 YRS0.0T0.0T0.61.53.73.31.70.4T0.011.2

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