2001 Seattle, Washington Seattle – Tacoma Airport (SEA)

views updated

2001 SEATTLE, WASHINGTON SEATTLE – TACOMA AIRPORT (SEA)

The Seattle–Tacoma International Airport is located 6 miles south of the Seattle city limits and 14 miles north of Tacoma. It is situated on a low ridge lying between Puget Sound on the west and the Green River valley on the east with terrain sloping moderately to the shores of Puget Sound some 2 miles to the west. The Olympic Mountains, rising sharply from Puget Sound, are about 50 miles to the northwest. Rather steep bluffs border the Green River Valley about 2.5 miles to the east and the foothills of the Cascade Range begin 10 to 15 miles to the east of the airport.

The mild climate of the Pacific Coast is modified by the Cascade Mountains and, to a lesser extent, by the Olympic Mountains. The climate is characterized by mild temperatures, a pronounced though not sharply defined rainy season, and considerable cloudiness, particularly during the winter months. The Cascades are very effective in shielding the Seattle–Tacoma area from the cold, dry continental air during the winter and the hot, dry continental air during the summer months. The extremes of temperature that occur in western Washington are the result of the occasional pressure distributions that force the continental air into the Puget Sound area. But the prevailing southwesterly circulation keeps the average winter daytime temperatures in the 40s and the nighttime readings in the 30s. During the summer, daytime temperatures are usually in the 70s with nighttime lows in the 50s. Extremes of temperatures, both in the winter and summer, are usually of short duration. The dry season is centered around July and early August with July being the driest month of the year. The rainy season extends from October to March with December normally the wettest month, however, precipitation is rather evenly distributed through the winter and early spring months with more than 75 percent of the yearly precipitation falling during the winter wet season. Most of the rainfall in the Seattle area comes from storms common to the middle latitudes. These disturbances are most vigorous during the winter as they move through western Washington. The storm track shifts to the north during the summer and those that reach the State are not the wind and rain producers of the winter months. Local summer afternoon showers and a few thunderstorms occur in the Seattle–Tacoma area but they do not contribute materially to the precipitation.

The occurrence of snow in the Seattle–Tacoma area is extremely variable and usually melts before accumulating measurable depths. There are winters on record with only a trace of snow, but at the other extreme, over 21 inches has fallen in a 24–hour period. Usually, winter storms do not produce snow unless the storm moves in such a way to bring cold air out of Canada directly or with only a short over water trajectory.

The highest winds recorded in the Seattle–Tacoma area were associated with strong storms crossing the state from the southwest. Prevailing winds are from the southwest but occasional severe winter storms will produce strong northerly winds. Winds during the summer months are relatively light with occasional land–sea breeze effects creating afternoon northerly winds of 8 to 15 miles an hour. Fog or low clouds that form over the southern Puget Sound area in the late summer, fall, and early winter months, often dominate the weather conditions during the late night and early morning hours with visibilities occasionally lower for a few hours near sunrise. Most of the summer clouds form along the coast and move into the Seattle area from the southwest.

Based on the 1951–1980 period, the average first occurrence of 32 degrees Fahrenheit in the fall is November 11 and the average last occurrence in the spring is March 24.

NORMALS, MEANS, AND EXTREMES

SEATTLE, WA (SEA)

LATITUDE:    LONGITUDE:    ELEVATION (FT):    TIME ZONE:    WBAN: 24233

47 27′ 41″ N  122 18′ 49″ W  GRND: 447  BARO: 450  PACIFIC (UTC + 8)

ELEMENTPORJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECYEAR
TEMPERATURE FNORMAL DAILY MAXIMUM3045.049.552.757.263.969.975.275.269.359.750.545.159.4
MEAN DAILY MAXIMUM5444.648.852.257.364.069.375.074.869.559.450.645.459.2
HIGHEST DAILY MAXIMUM576470758593961009998897464100
YEAR OF OCCURRENCE198119681987197619631995199419811988198719491993JUL 1994
MEAN OF EXTREME MAXS.5455.259.764.473.181.184.889.188.184.373.161.055.572.4
NORMAL DAILY MINIMUM3035.237.438.541.246.351.955.255.751.945.840.135.844.6
MEAN DAILY MINIMUM5434.736.637.941.146.451.354.654.851.245.239.635.844.1
LOWEST DAILY MINIMUM57011129283843443528660
YEAR OF OCCURRENCE195019501955197519541952195419551972194919551968JAN 1950
MEAN OF EXTREME MINS.5421.925.429.233.838.445.249.049.043.034.728.224.135.2
NORMAL DRY BULB3040.143.545.649.255.160.965.265.560.652.845.340.552.0
MEAN DRY BULB5439.642.845.049.255.360.364.964.760.452.345.140.651.7
MEAN WET BULB1839.139.842.745.950.454.157.858.255.249.142.938.347.8
MEAN DEW POINT1835.635.538.441.245.649.352.553.350.745.940.035.143.6
NORMAL NO. DAYS WITH:
MAXIMUM 90300.00.00.00.00.20.31.11.20.30.00.00.03.1
MAXIMUM 32301.20.20.00.00.00.00.00.00.00.00.21.32.9
MINIMUM 32309.65.33.00.20.00.00.00.00.00.23.68.630.5
MINIMUM 0300.00.00.00.00.00.00.00.00.00.00.00.00.0
H/CNORMAL HEATING DEG. DAYS3077260260147430714458651563785917604908
NORMAL COOLING DEG. DAYS300000021648124000190
RHNORMAL (PERCENT)3078757471696765687379808073
HOUR 04 LST3081808283828181838686848283
HOUR 10 LST3079777471686665687379808173
HOUR 16 LST3074676157545349505767757762
HOUR 22 LST3078767574727068707581818075
SPERCENT POSSIBLE SUNSHINE3028405052565664656243282347
W/OMEAN NO. DAYS WITH:
HEAVY FOG(VISBY 1/4 MI)574.83.22.31.10.70.71.52.54.96.95.05.939.5
THUNDERSTORMS570.20.30.61.00.90.70.70.80.70.40.80.37.4
CLOUDINESSMEAN:
SUNRISE-SUNSET (OKTAS)526.76.56.36.25.75.64.24.54.85.96.66.75.8
MIDNIGHT-MIDNIGHT (OKTAS)326.66.15.85.95.55.34.14.24.45.36.36.45.5
MEAN NO. DAYS WITH:
CLEAR522.83.03.42.74.45.110.29.08.14.02.52.357.5
PARTLY CLOUDY523.94.25.87.38.87.99.59.78.57.44.23.981.1
CLOUDY5224.321.121.920.017.716.910.511.913.019.523.324.9225.0
PRMEAN STATION PRESSURE(IN)2929.5529.5229.5029.5529.5529.5629.5729.5429.5529.5729.5329.5829.55
MEAN SEA-LEVEL PRES. (IN)1830.0430.0230.0130.0430.0230.0330.0530.0330.0330.0630.0230.0830.04
WINDSMEAN SPEED (MPH)519.69.69.59.48.98.68.27.98.18.49.29.68.9
PREVAIL. DIR (TENS OF DEGS)3519191921212122210119191819
MAXIMUM 2-MINUTE:
SPEED (MPH)540374429252622223632373744
DIR. (TENS OF DEGS)20231922212222012018202219
YEAR OF OCCURRENCE200019991999200120011999200119971999199719982000MAR 1999
MAXIMUM 5-SECOND:
SPEED (MPH)552496040363231294344484860
DIR. (TENS OF DEGS)20211821272323342118212218
YEAR OF OCCURRENCE200019991999200119991999199919981999199719982000MAR 1999
PRECIPITATIONNORMAL (IN)305.383.993.542.331.701.500.761.141.883.235.835.9137.19
MAXIMUM MONTHLY (IN)5712.929.118.406.534.763.902.394.595.958.9511.6211.8512.92
YEAR OF OCCURRENCE195319611950199119481946198319751978194719981979JAN 1953
MINIMUM MONTHLY (IN)570.580.350.570.330.120.13T0.01T0.310.741.37T
YEAR OF OCCURRENCE198519931965195619921951196019741991198719761978SEP 1991
MAXIMUM IN 24 HOURS (IN)573.223.412.863.321.832.080.851.752.233.743.582.613.74
YEAR OF OCCURRENCE198619511972199119691985198119681978198119901979OCT 1981
NORMAL NO. DAYS WITH:
PRECIPITATION 0.013018.015.416.813.610.68.45.06.19.112.217.618.7151.5
PRECIPITATION 1.00300.80.40.20.10.10.20.00.10.20.41.21.14.8
SNOWFALLNORMAL (IN)304.11.20.70.1T0.00.00.00.00.11.13.110.4
MAXIMUM MONTHLY (IN)5257.213.118.22.3T0.0T0.0T2.017.522.157.2
YEAR OF OCCURRENCE1950194919511972199319801972197119851968JAN 1950
MAXIMUM IN 24 HOURS (IN)5221.49.87.42.3T0.0T0.0T2.09.413.021.4
YEAR OF OCCURRENCE1950199019891972199319801972197119461968JAN 1950
MAXIMUM SNOW DEPTH (IN)4721117200000281021
YEAR OF OCCURRENCE1969196919891972197119851974JAN 1969
NORMAL NO. DAYS WITH:
SNOWFALL 1.0301.40.30.30.10.00.00.00.00.00.*0.31.03.4
PRECIPITATION (inches) 2001 SEATTLE, WASHINGTON WA (SEA)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
19727.248.116.744.120.691.811.341.134.100.723.388.9848.36
19734.291.891.621.351.602.500.080.271.813.317.998.3335.04
19747.784.015.842.391.371.251.510.010.211.995.066.4537.87
19756.015.802.872.491.130.840.274.59T7.755.077.6644.48
19765.554.742.711.671.610.631.172.711.252.060.741.8626.70
19771.771.583.800.553.700.540.423.592.552.605.276.4732.84
19784.303.592.434.191.790.751.401.195.950.986.051.3733.99
19792.255.321.550.810.880.460.731.022.073.381.9411.8532.26
19804.095.042.103.230.971.770.460.641.431.327.167.3935.60
19812.424.452.231.581.332.311.380.253.426.404.075.5635.40
19825.357.573.732.070.631.030.590.621.494.075.316.8639.32
19837.074.573.811.062.101.852.391.901.851.347.975.0240.93
19843.623.913.912.873.382.810.170.131.012.148.094.9536.99
19850.582.632.561.300.852.800.100.551.985.744.261.7825.13
19868.544.412.671.381.710.681.100.101.894.217.983.6738.34
19875.982.055.532.612.380.160.390.290.910.313.216.1129.93
19884.070.713.753.203.011.560.500.281.752.248.433.4832.98
19892.783.435.792.802.781.140.640.890.542.986.134.7934.69
19909.413.722.582.541.983.050.580.710.055.7910.713.6344.75
19914.464.694.666.531.391.290.282.17T1.315.333.3135.42
19927.823.091.684.120.121.140.890.661.152.455.574.0932.78
19934.090.354.804.542.862.481.270.160.031.542.204.4828.80
19942.514.473.172.271.431.250.280.301.693.515.798.1534.82
19954.484.974.072.050.811.461.341.810.913.9310.406.3742.60
19967.348.352.065.372.070.590.771.321.855.545.2310.1850.67
19977.021.998.154.321.871.641.201.273.415.833.932.6343.26
19987.153.313.960.991.981.110.410.350.723.4811.628.9844.06
19996.846.953.661.492.121.861.180.920.172.269.605.0642.11
20003.775.252.821.483.271.610.230.331.123.003.272.5128.66
20012.702.072.733.161.393.051.032.320.833.139.265.8937.56
POR=58 YRS5.584.273.732.571.721.530.721.021.763.565.965.8338.25
AVERAGE TEMPERATURE (F) 2001 SEATTLE, WASHINGTON WA (SEA)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
197237.041.446.947.058.360.166.066.755.450.146.738.151.1
197338.743.944.148.656.559.364.761.661.952.243.744.451.6
197438.743.246.350.354.962.664.064.664.452.545.142.452.4
197538.840.842.945.854.660.767.563.263.051.444.941.551.3
197641.840.941.349.556.460.065.964.162.654.947.844.752.5
197739.448.745.753.654.563.065.168.558.952.243.942.253.0
197844.446.048.649.954.564.365.865.558.854.341.237.552.6
197937.842.349.350.857.262.567.464.062.654.243.944.153.0
198034.843.844.351.654.257.563.861.959.653.946.744.151.4
198144.444.248.849.654.757.563.368.161.150.947.241.752.6
198239.342.144.147.454.763.162.865.160.652.743.240.851.3
198345.046.949.450.757.759.963.365.658.351.747.836.152.7
198443.244.848.548.752.958.865.064.959.949.744.636.851.5
198537.139.043.349.254.860.068.665.258.151.435.836.249.9
198644.942.849.248.155.762.761.768.459.154.345.342.052.9
198740.546.348.952.056.962.664.266.162.655.848.539.253.6
198840.144.445.650.354.959.665.365.460.555.445.441.952.4
198940.535.943.753.456.063.264.565.364.153.147.042.952.5
199042.540.047.152.154.759.868.067.363.451.246.635.352.3
199140.047.744.149.154.358.966.866.662.952.947.343.752.9
199243.947.350.353.159.865.066.766.860.054.445.538.854.3
199337.942.348.150.659.660.661.265.561.955.442.041.452.2
199444.940.448.552.358.260.667.967.364.452.842.441.753.5
199546.445.947.851.860.162.767.063.064.052.549.142.454.4
199639.743.247.251.553.160.567.966.559.251.143.139.351.9
199741.141.944.849.258.259.564.567.762.251.348.441.552.5
199842.245.846.650.454.959.967.666.863.152.646.739.953.0
199942.042.544.348.551.858.262.464.860.852.247.942.051.5
200040.343.744.550.953.860.664.363.560.252.842.540.851.5
200142.040.745.448.055.457.662.564.859.850.946.741.551.3
POR=57 YRS39.642.844.949.155.360.364.964.660.252.345.040.551.6

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 SEATTLE, WASHINGTON WA (SEA)
YEARJULAUGSEPOCTNOVDECJANFEBMARAPRMAYJUNTOTAL
1972-7348322954555448258075866394842721835170
1973-7470114111388633632809606573433306994774
1974-756066743805916908046716785703171445045
1975-762373934135947237126937314652651574942
1976-77245281307510625786451591335320794161
1977-783443178390625701631525498447323784473
1978-794442180324706846837630479420235964839
1979-802740863276286429296106343953292184865
1980-81661041583435436396335774944553162204548
1981-8280281384305307157906366405213121034923
1982-8393421413736477456135024794222441494450
1983-8472191964065118906725775074823721834887
1984-8554421594676038678577196664693101605373
1985-86848199413870888618616479502305905036
1986-87105121963235867077545224913842531054438
1987-8858371022844857927675905934353161654624
1988-896038162291583708749807654340273934758
1989-904129683625346776896965473793121584492
1990-912923614205469137674756394723221794846
1991-92244090368526654645507447351171633886
1992-9326221513225808058346295174271701354618
1993-94113481202906857236186825033732091324496
1994-95235433696717135705275273901601184116
1995-961977603824716937796305433993621354550
1996-9742321674226497937326406224682111594937
1997-983811954164897187005335624333071524454
1998-992121793765437717066236344874002184879
1999-00101421413935047067606116284153401544795
2000-0160651463736687457076755995043052185065
2001-8644150430547723
COOLING DEGREE DAYS (base 65 F) 2001 SEATTLE, WASHINGTON WA (SEA)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
19720000223859111000212
197300001619671721000140
19740000036386260000196
197500000211082939000197
19760008414592915000129
19770000026441584000232
1978000046676640000210
197900002271061521000171
19800000003415320054
19810000133513124000194
19820000053315515000154
198300002422444000094
1984000015624511000124
19850000317125590000204
1986000022271012426000209
198700001142398035500212
19880000710795636100189
19890000247324546000172
1990000001012910021000260
1991000000859634000215
19920000186883858000262
1993000010817232000123
19940000151208629000241
199500001555882034000212
1996000102137811000222
19970000402910017000150
19980002161088429000230
19990000018294322000112
2000000002844278000107
200100001131444000072
SNOWFALL (inches) 2001 SEATTLE, WASHINGTON WA (SEA)
YEARJULAUGSEPOCTNOVDECJANFEBMARAPRMAYJUNTOTAL
1972-730.00.0T0.0T5.62.7T0.8T0.00.09.1
1973-740.00.00.00.00.20.33.7TT0.0T0.04.2
1974-750.00.00.00.00.09.81.3TT0.20.00.011.3
1975-760.00.00.00.01.62.6T0.50.2T0.00.04.9
1976-770.00.00.00.00.0T1.0T0.90.00.00.01.9
1977-780.00.00.00.03.5TT0.0TT0.00.03.5
1978-790.00.00.00.04.90.20.50.40.00.00.00.06.0
1979-800.00.00.00.00.01.28.82.50.1T0.00.012.6
1980-81T0.00.00.0T0.30.01.10.00.00.00.01.4
1981-820.00.00.00.00.0T7.0T2.0T0.00.09.0
1982-830.00.00.0T0.0T0.00.00.00.00.00.0T
1983-840.00.00.00.0T0.3T0.00.0T0.00.00.3
1984-850.00.00.0TT2.4T5.7TT0.00.08.1
1985-860.00.00.0T17.51.70.01.10.0T0.00.020.3
1986-870.00.00.00.0T0.01.40.00.00.00.00.01.4
1987-880.00.00.00.00.0TT0.0T0.00.00.0T
1988-890.00.00.00.0TT1.05.87.4TT0.014.2
1989-900.00.00.00.00.00.0T9.8T0.0T0.09.8
1990-910.00.00.00.00.03.80.40.02.5T0.00.06.7
1991-920.00.00.00.00.00.00.00.00.00.00.00.00.0
1992-930.00.00.00.0T6.71.31.40.00.0T0.09.4
1993-940.00.00.00.0T0.00.02.10.20.00.00.02.3
1994-950.00.00.00.0T1.90.00.2T0.00.00.02.1
1995-960.00.00.00.00.00.010.50.50.00.00.00.011.0
1996-970.00.00.0
1997-98
1998-99
1999-00
2000-01
2001-
POR=51 YRST0.0T0.01.12.44.81.61.30.1T0.011.3

More From encyclopedia.com

About this article

2001 Seattle, Washington Seattle – Tacoma Airport (SEA)

Updated About encyclopedia.com content Print Article

You Might Also Like

    NEARBY TERMS

    2001 Seattle, Washington Seattle – Tacoma Airport (SEA)