2001 Roanoke, Virginia (ROA)

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2001 ROANOKE, VIRGINIA (ROA)

The climate of Roanoke is relatively mild. Roanoke is nestled among mountains which interrupt the Great Valley, extending from northernmost Virginia southwestward into east Tennessee. This location, at a point where the valley is pinched between the Blue Ridges and the Alleghenies, offers a natural barrier to the winter cold as it moves southward. It is also far enough inland that hurricanes lose much of their destructive force before reaching Roanoke. Finally, the rough terrain is an inhospitable breeding ground for tornadic activity. The elevation in the vicinity usually produces cool summer nights that make a light cover comfortable for sleeping. Although past records show extremes over 100 degrees and below zero, many years pass without either extreme being threatened.

Roanoke is located near the headwaters of the Roanoke River, which flows in a general southeasterly direction. Numerous creeks and small streams from nearby mountainous areas empty into the Roanoke River. The usual low water stage is 1 to 1.5 feet, and flood stage is 10 feet. Some low–lying streets in Roanoke and nearby Salem have to be blocked off during 7 to 8 foot stages, but damage is minor until the river overflows its banks. The highest stage on record exceeds 19 feet. Damage has been widespread on occasion and has amounted to several million dollars in the city of Roanoke alone.

The growing season averages 190 days. The average date of the last freezing temperature in spring is mid–April and the average date of the first freezing date in the fall is late October.

Rainfall is well apportioned throughout the year. Droughts are so infrequent that quoting actual records would be difficult. Snow usually falls each winter, ranging from only a trace to more than 60 inches.

NORMALS, MEANS, AND EXTREMES

ROANOKE, VA (ROA)

LATITUDE:    LONGITUDE:    ELEVATION (FT):    TIME ZONE:    WBAN:    13741

37 19′ 01″ N  79 58′ 27″ W  GRND:  1189  BARO:  1192  EASTERN  (UTC + 5)

ELEMENTPORJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECYEAR
TEMPERATURE FNORMAL DAILY MAXIMUM3043.847.357.867.375.782.986.485.378.568.158.047.666.6
MEAN DAILY MAXIMUM5445.148.656.867.776.183.487.085.478.768.857.547.766.9
HIGHEST DAILY MAXIMUM547880879596100104105101938380105
YEAR OF OCCURRENCE195219851986195719621959195419831954195119501998AUG 1983
MEAN OF EXTREME MAXS.5465.869.677.885.589.393.495.894.591.383.375.067.282.4
NORMAL DAILY MINIMUM3025.027.235.743.852.560.264.863.856.844.837.028.945.0
MEAN DAILY MINIMUM5426.928.835.644.653.060.965.564.157.045.636.829.445.7
LOWEST DAILY MINIMUM54-11-19203139474234229-4-11
YEAR OF OCCURRENCE198519961996198519661977198819861983197619501983JAN 1985
MEAN OF EXTREME MINS.548.812.419.728.738.547.854.953.541.630.120.712.230.7
NORMAL DRY BULB3034.537.346.855.664.171.575.674.667.756.547.538.355.8
MEAN DRY BULB5436.038.846.256.264.772.076.374.867.957.147.038.656.3
MEAN WET BULB1731.634.640.148.457.465.468.967.958.251.242.231.949.8
MEAN DEW POINT1723.125.430.539.951.961.365.064.454.445.135.024.443.4
NORMAL NO. DAYS WITH:
MAXIMUM 90300.00.00.00.40.85.610.27.82.50.00.00.027.3
MAXIMUM 32305.12.70.10.00.00.00.00.00.00.00.12.910.9
MINIMUM 323023.320.012.22.60.10.00.00.00.02.89.820.090.8
MINIMUM 0300.40.00.00.00.00.00.00.00.00.00.00.20.6
H/CNORMAL HEATING DEG. DAYS30946776564289105500392835258284360
NORMAL COOLING DEG. DAYS3000077820032929812020001052
RHNORMAL (PERCENT)3061605857666971737468646465
HOUR 01 LST3066656464768384868680726975
HOUR 07 LST3069707070798183878883767277
HOUR 13 LST3052514846525354565652525452
HOUR 19 LST3057555148586264666863606159
SPERCENT POSSIBLE SUNSHINE
W/OMEAN NO. DAYS WITH:
HEAVY FOG(VISBY 1/4 MI)542.62.72.01.01.71.01.31.52.41.92.12.322.5
THUNDERSTORMS540.10.21.12.96.16.68.36.32.60.90.40.135.6
CLOUDINESSMEAN:
SUNRISE-SUNSET (OKTAS)485.15.05.04.85.04.84.74.64.53.94.64.84.7
MIDNIGHT-MIDNIGHT (OKTAS)324.74.64.74.34.54.34.34.24.23.74.34.64.4
MEAN NO. DAYS WITH:
CLEAR498.17.68.18.57.47.16.97.89.612.88.88.7101.4
PARTLY CLOUDY497.77.18.48.810.511.913.012.48.87.58.47.9112.4
CLOUDY4915.213.614.412.713.011.111.110.811.610.712.814.4151.4
PRMEAN STATION PRESSURE(IN)2828.8228.8128.7728.7528.7728.7828.8128.8428.8628.8728.8628.8428.82
MEAN SEA-LEVEL PRES. (IN)1730.1130.1030.0329.9929.9930.0030.0230.0530.0730.1230.1330.1330.06
WINDSMEAN SPEED (MPH)429.39.29.79.57.56.76.46.05.96.77.78.47.8
PREVAIL. DIR (TENS OF DEGS)2630303030302727273130313030
MAXIMUM 2-MINUTE:
SPEED (MPH)544363839393440343433373744
DIR. (TENS OF DEGS)28302830263504323030252728
YEAR OF OCCURRENCE200019991997199920011998199719971999200019992000JAN 2000
MAXIMUM 5-SECOND:
SPEED (MPH)553475351514147494539474753
DIR. (TENS OF DEGS)28202929263604282929242728
YEAR OF OCCURRENCE200019981997199920011998199719971999200019992000JAN 2000
PRECIPITATIONNORMAL (IN)302.623.043.483.253.983.193.914.153.503.853.192.9741.13
MAXIMUM MONTHLY (IN)547.978.007.9111.358.4210.3210.099.5411.099.8912.367.1012.36
YEAR OF OCCURRENCE199819981993198719501995198919841987199019851948NOV 1985
MINIMUM MONTHLY (IN)540.290.560.430.481.040.620.450.740.150.020.440.180.02
YEAR OF OCCURRENCE198119681966197619971986197719951991200019601965OCT 2000
MAXIMUM IN 24 HOURS (IN)543.643.323.095.573.993.982.745.226.606.416.633.406.63
YEAR OF OCCURRENCE199519941998197819731972198919851987196819851948NOV 1985
NORMAL NO. DAYS WITH:
PRECIPITATION 0.01309.69.310.510.012.09.711.610.68.37.88.69.2117.2
PRECIPITATION 1.00300.50.60.70.70.90.70.91.20.91.30.70.59.6
SNOWFALLNORMAL (IN)307.38.13.20.6T0.00.00.00.00.*1.74.825.7
MAXIMUM MONTHLY (IN)4941.227.630.37.3TT0.00.0T1.013.822.641.2
YEAR OF OCCURRENCE1966196019601971199019891953195719681966JAN 1966
MAXIMUM IN 24 HOURS (IN)4922.218.417.47.3TT0.00.0T1.010.016.422.2
YEAR OF OCCURRENCE1996198319601971199019891953195719681969JAN 1996
MAXIMUM SNOW DEPTH (IN)48231817300000081523
YEAR OF OCCURRENCE198719831960198719501969JAN 1987
NORMAL NO. DAYS WITH:
SNOWFALL 1.0301.71.90.70.20.00.00.00.00.00.00.51.16.1
PRECIPITATION (inches) 2001 ROANOKE, VA (ROA)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
19722.494.801.763.316.007.554.892.624.793.185.634.6251.64
19732.602.955.925.395.583.655.103.341.844.281.795.6048.04
19743.332.133.121.863.762.933.714.933.040.771.283.1634.02
19753.593.057.802.046.651.545.155.686.463.011.773.6750.41
19762.161.274.540.486.135.201.242.203.179.721.312.5940.01
19771.460.732.613.501.522.410.452.292.714.706.462.4931.33
19786.120.655.927.544.852.054.836.330.520.782.553.1545.29
19795.275.373.383.992.655.783.973.379.183.563.771.1351.42
19804.100.675.415.512.661.815.182.871.662.301.780.6034.55
19810.292.432.301.754.562.492.861.324.523.900.683.7930.89
19823.764.752.332.014.834.993.985.202.674.133.652.5344.83
19831.284.126.417.953.172.381.672.231.527.734.265.6148.33
19841.354.854.303.974.492.344.179.542.691.422.671.8443.63
19852.453.641.801.756.892.084.188.671.263.7712.360.8549.70
19860.932.871.361.674.150.622.834.313.042.763.735.4833.75
19874.534.554.1111.352.680.713.211.0811.091.105.002.1651.57
19881.871.070.883.402.763.663.754.303.011.262.421.2829.66
19891.312.042.962.546.467.7610.091.658.944.133.862.6054.34
19902.332.763.422.077.450.833.804.421.869.891.083.7943.70
19913.552.107.582.492.882.427.222.310.150.042.513.8137.06
19922.513.752.544.896.066.871.732.382.071.905.602.6242.92
19933.773.447.912.772.372.491.241.044.582.152.605.2739.63
19944.525.345.675.591.691.997.074.220.761.841.532.4142.63
19957.281.881.310.794.5510.322.340.742.043.493.392.3240.45
19966.872.123.751.764.587.652.636.4010.141.574.752.7254.94
19972.182.213.122.511.045.433.382.223.431.502.652.3732.04
19987.978.005.204.584.472.030.866.171.101.470.852.3245.02
19993.702.142.772.702.270.855.962.637.381.242.092.4636.19
20002.081.692.865.712.674.577.163.165.880.022.081.6739.55
20011.790.904.480.814.671.513.132.022.120.430.602.4824.94
POR=54 YRS3.003.153.673.633.853.523.723.893.413.062.822.9440.66
AVERAGE TEMPERATURE (F) 2001 ROANOKE, VA (ROA)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
197239.636.045.655.562.067.774.373.267.652.245.444.555.3
197337.335.851.153.861.173.875.576.070.859.249.338.256.8
197445.339.050.857.264.368.174.573.564.855.047.338.956.6
197539.640.442.252.966.571.574.577.066.660.051.138.856.8
197633.446.750.857.462.370.074.072.165.250.340.234.354.7
197723.636.652.558.968.171.179.777.870.453.648.535.956.4
197827.829.544.256.363.872.776.077.571.454.049.539.555.2
197931.429.448.655.763.869.373.574.066.354.649.640.954.8
198037.534.043.556.764.870.078.176.871.555.545.438.756.0
198132.038.243.158.660.974.076.173.466.153.745.232.854.5
198228.738.144.850.867.570.175.572.365.857.447.842.455.1
198335.636.547.052.461.070.177.077.968.157.147.134.955.4
198433.643.643.354.263.174.273.274.464.164.346.047.156.8
198531.338.650.361.967.172.776.573.868.460.355.435.157.6
198635.238.347.258.863.974.278.872.468.959.047.438.556.9
198734.236.946.653.267.175.079.377.868.951.549.641.456.8
198830.837.947.555.463.470.977.177.566.051.246.738.955.3
198941.338.247.454.361.273.775.974.168.158.546.029.655.7
199043.745.951.556.064.372.676.874.668.459.252.243.859.1
199139.342.749.257.569.673.577.974.869.359.446.842.458.5
199239.641.546.555.560.268.477.072.168.055.546.338.555.8
199339.736.042.154.565.671.980.376.868.655.347.336.256.2
199430.639.446.760.960.675.177.673.966.956.751.443.056.9
199538.536.950.156.864.472.076.978.667.558.543.235.556.6
199633.738.241.756.365.272.874.473.366.158.041.040.255.1
199735.843.049.752.560.369.276.173.467.756.343.638.355.5
199841.242.245.856.567.173.577.575.973.659.049.043.458.7
199939.842.044.058.264.372.379.275.566.455.752.842.557.7
200035.343.551.754.867.673.873.372.965.959.444.231.156.1
200137.042.943.459.564.873.374.376.966.556.953.244.357.8
POR=54 YRS36.038.946.356.664.772.076.374.867.957.147.138.656.4

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 ROANOKE, VA (ROA)
YEARJULAUGSEPOCTNOVDECJANFEBMARAPRMAYJUNTOTAL
1972-731013339158262885281242834414414226
1973-74001219646182660772244025596143629
1974-75008430853980178368369936160124330
1975-760059173415809973523438271126223809
1976-770347452735945127578638520356234910
1977-780018350496896114798963726111244910
1978-790029335461784103799251227988154532
1979-80394932945873884889365626678144341
1980-810030301582807101674467221215834525
1981-82005835758999111217466184215134955
1982-830661264509695904792551381157144334
1983-84108724653192496661466433612364498
1984-850012074565549104173447116839113772
1985-86005517128291891773955120611513955
1986-87022222315238139507825623525804315
1987-8800184124557231055778535289101464412
1988-89105342354380272674355634017204359
1989-90036323456010916545284412977733951
1990-9100382003816527876184862453643447
1991-920049194539695777677567290172183978
1992-93025529055281377780769831052124368
1993-940052300529886106170955917217644448
1994-9500222614016758157794542589303758
1995-96005422664790896577171728311864695
1996-970052221712762898610467369175494315
1997-98103229463481973062961525546224077
1998-9900101844736627756386462236183680
1999-0053382893576899136194143014453677
2000-01208619061710468636126662216644373
2001-4070263345638
COOLING DEGREE DAYS (base 65 F) 2001 ROANOKE, VA (ROA)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
19720002613118305262118020844
1973003152926933134619223001208
19740072782117303267833120901
1975000510821330137911427501152
1976008534917928523058100863
1977007281582144614001854701464
19780007792433473912282001297
19790010756150273296971210902
1980000217817141237423113001300
198100226392783502679713001072
198200001371653322429035001001
1983000114117238240718810001211
1984000207129026030110156001099
198501187811224736528016334301301
1986004248428243825714548001282
198700041303064504031400001433
1988000758232386395901001169
19890017276126534429316338001208
19900029346123837730514527301219
19910022918826740731118528101418
19920021229125377230152400931
19930002782264813741668601341
19940005745317397286849301198
1995000208022037542713430001286
1996010301302473002639310001074
19970001361813532641213100987
1998002451202823943442767001452
19990002647233451336869001188
20000010413127726925312125001090
2001000646725930137712120001209
SNOWFALL (inches) 2001 ROANOKE, VA (ROA)
YEARJULAUGSEPOCTNOVDECJANFEBMARAPRMAYJUNTOTAL
1972-730.00.00.00.0TT2.41.45.50.20.00.09.5
1973-740.00.00.0TT7.9T9.7T0.00.00.017.6
1974-750.00.00.0T3.36.64.66.36.2T0.00.027.0
1975-760.00.00.00.0T0.1TT2.20.00.00.02.3
1976-770.00.00.00.02.46.48.91.5TT0.00.019.2
1977-780.00.00.0T2.40.414.59.610.40.00.00.037.3
1978-790.00.00.00.01.6T3.019.3T0.00.00.023.9
1979-800.00.00.00.3T0.215.14.212.0T0.00.031.8
1980-810.00.00.0TTT1.4T10.40.00.00.011.8
1981-820.00.00.00.04.03.98.412.20.51.90.00.030.9
1982-830.00.00.0T0.06.23.824.30.30.40.00.035.0
1983-840.00.00.00.0T0.67.21.50.30.20.00.09.8
1984-850.00.00.00.0T0.82.71.21.3T0.00.06.0
1985-860.00.00.00.00.01.21.77.1TT0.00.010.0
1986-870.00.00.00.0TT27.919.12.76.30.00.056.0
1987-880.00.00.00.01.7T6.7TTT0.00.08.4
1988-890.00.00.0T0.03.80.79.10.20.2TT14.0
1989-900.00.00.00.03.311.1T0.21.50.0T0.016.1
1990-910.00.00.00.00.00.8TT0.40.00.00.01.2
1991-920.00.00.00.0TT0.42.20.51.90.00.05.0
1992-930.00.00.00.0T0.90.110.716.00.30.00.028.0
1993-940.00.00.0TT6.25.21.83.1T0.00.016.3
1994-950.00.00.00.0T0.09.61.21.00.00.00.011.8
1995-960.00.00.00.00.410.228.217.10.1T
1996-97
1997-98
1998-99
1999-00
2000-01
2001-
POR=48 YRS0.00.0T0.01.53.96.66.83.60.4TT22.8

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