Parameter Codes for Weather Data

Code	Name	Unit	Network	Description
altimeter	Altimeter setting	in Hg	asos	Altimeter Setting in Inches of Mercury. Reported to nearest hundreth of an inch. It is the pressure "reduced" to mean sea level using the temperature profile of the "standard" atmosphere, which is representative of average conditions over the United States at 40 degrees north latitude. The altimeter setting is the pressure value to which an aircraft altimeter scale is set so that it will indicate the altitude (above mean sea level) of the aircraft on the ground at the location for which the pressure value was determined. The altimeter setting is an attempt to remove elevation effects from pressure readings using "standard" conditions.
avgperiod	Average wave period	sec	buoy
battmin	Battery Minimum	volts	econet
c1rdc	Soil dielectric constant level 1		scan
c1sal	Soil salinity level 1		scan
c1sm	Soil moisture level 1	m3/m3	econet,scan
c1tmp	Soil temperature level 1	C	econet,scan
c2rdc	Soil dielectric constant level 2		scan
c2sal	Soil salinity level 2		scan
c2sm	Soil moisture level 2	m3/m3	econet,scan
c2tmp	Soil temperature level 2	C	econet,scan
c3rdc	Soil dielectric constant level 3		scan
c3sal	Soil salinity level 3		scan
c3sm	Soil moisture level 3		econet,scan
c3tmp	Soil temperature level 3	C	econet,scan
c4rdc	Soil dielectric constant level 4		scan
c4sal	Soil salinity level 4		scan
c4sm	Soil moisture level 4		econet,scan
c4tmp	Soil temperature level 4	C	econet,scan
c5rdc	Soil dielectric constant level 5		scan
c5sal	Soil salinity level 5		scan
c5sm	Soil moisture level 5		econet,scan
c5tmp	Soil temperature level 5	C	econet,scan
calculated_dew	Calculated Dewpoint Temperature	C	econet	The dewpoint temperature is a measure of atmospheric moisture. It is the temperature to which air must be cooled in order to reach saturation (assuming air pressure and moisture content are constant). The values in this column are calculated from temperature and relative humidity.
calculated_dew10	Calculated Dewpoint Temperature	C	econet	--calculated_dew
calculated_evap_pm	Penman-Monteith estimate		econet	description...
calculated_evap_pm_ang	Penman-Monteith Potential ET -- Angstrom's Est. Radiation	mm	asos,awos,econet	The Food and Agriculture Organization of the United Nations (FAO) derived a standard Penman-Monteith method to determine the rate of moisture transport away from a surface (i.e., evaporation rate from water surfaces and transpiration rate from plant surfaces). This method requires measurements of net radiation, ground heat flux, temperature, humidity, and wind speed. Solar radiation measurements are not readily available at all stations, so the needed solar radiation measurement is replaced with the Angstrom radiation estimate. Angstrom's equation states that the incoming solar radiation is proportional to the extraterrestrial radiation and the relative sunlight duration. Extraterrestrial radiation is the idealized amount of radiation from the sun if it were striking a flat plane perpendicular to the sun's rays at the top of the atmosphere, over a certain latitude, and during a certain time of year and day. The relative sunlight duration is the ratio of the actual hours of daylight to the maximum number of possible daylight hours for a given location, as a function of latitude and time of year.
calculated_evap_pm_har	Penman-Monteith Potential ET -- Hargreaves' Est. Radiation	mm	asos,awos,econet	The Food and Agriculture Organization of the United Nations (FAO) derived a standard Penman-Monteith method to determine the rate of moisture transport away from a surface (i.e., evaporation rate from water surfaces and transpiration rate from plant surfaces). This method requires measurements of net radiation, ground heat flux, temperature, humidity, and wind speed. Solar radiation measurements are not readily available at all stations, so the needed solar radiation measurement is replaced with the Hargreaves radiation estimate. Hargreaves' equation states that the incoming solar radiation is proportional to the extraterrestrial radiation, the square root of the difference between daily maximum and minimum temperatures, and a coefficient for the proximity to water. Extraterrestrial radiation is the idealized amount of radiation from the sun if it were striking a flat plane perpendicular to the sun's rays at the top of the atmosphere, over a certain latitude, and during a certain time of year and day. The coefficient for the proximity to water ranges from 0.16 for interior locations to 0.19 for coastal locations. Due to North Carolina's relative location, a value of 0.18 is used for the entire state.
calculated_evap_pt	Priestley-Taylor estimate		econet	description...
calculated_HI	Calculated Heat Index		econet,asos	Heat Index is an index that combines air temperature and relative humidity to estimate how hot it actually feels. The human body cools off through perspiration, which removes heat from the body by convection or evaporation. Higher humidity prevents evaporation slowing our natural cooling ability. This is why humid days feel hotter than the actual temperature.
calculated_WC	Calculated Wind Chill		econet,asos	How cold is it outside? Simply knowing the temperature doesn't tell you enough about the conditions to enable you to dress sensibly for all winter weather. Other factors including wind speed, relative humidity and sunshine play important roles in determining how cold you feel outside. A description of the character of weather known as "coldness" was proposed about 1940 by scientists working in the Antarctic. The "wind chill index" was developed to describe the relative discomfort/danger resulting from the combination of wind and temperature. On November 1, 2001, the National Weather Service began using a new wind chill index. The reason for the change is to improve upon the current index, which is based on the 1945 Siple and Passel Index. During the Fall of 2000, the Office of the Federal Coordinator for Meteorological Services and Supporting Research (OFCM) formed a special group consisting of several Federal agencies, MSC, the academic research community (Indiana University-Purdue University in Indianapolis (IUPUI), University of Delaware, and University of Missouri), and the International Society of Biometeorology. Their job was to evaluate the existing wind chill formula and make necessary changes to improve upon it. The group is called the Joint Action Group for temperature Indices (JAG/TI) and is chaired by the NWS. Weird name, but very important work. The goal of JAG/TI is to internationally upgrade and standardize the index for temperature extremes (a.k.a. Wind Chill Index). They ultimately reached an agreement on a new wind chill formula. It will make use of the advances in science, technology, and computer modeling to provide a more accurate, understandable, and useful formula for calculating wind chill. Lots of time and energy was put into coming up with the new formula and what it does differently. Specifically, the new wind chill index will use wind speed calculated at the average height (5 feet) of the human body's face instead of 33 feet (the standard anemometer height); be based on a human face model; incorporate modern heat transfer theory (heat loss from the body to its surroundings, during cold and breezy/windy days); lower the calm wind threshold to 3 mph; use a consistent standard for skin tissue resistance; and assume the worst case scenario for solar radiation (clear night sky). In 2002, adjustments for solar radiation (i.e., the impact of sun) for a variety of sky conditions (sunny, partly sunny and cloudy) will be added to the calculation model Wind chill does not affect your car's antifreeze protection. It will have an impact on how quickly your home's exposed water pipes freeze, but has little impact on whether they would freeze or not. The importance of the wind chill index is as an indicator of how to dress properly for winter weather. In dressing for cold weather an important factor to remember is that entrapped insulating air warmed by body heat is the best protection against the cold. Consequently, wear loose-fitting, lightweight, warm clothing in several layers. Outer garments should be tightly- woven, water-repellant and hooded. Mittens snug at the wrist are better protection than fingered gloves.
calculated_wetbulb	Calculated Wet Bulb Temperature		asos	The temperature an air parcel would have if you cooled it adiabatically to saturation at constant pressure by evaporation of water into it, all latent heat being supplied by the parcel. This is different from the dew point in that you are adding moisture to the parcel as you cool. Thus the virtual temperature will always be equal to or greater than the dew point and the actual temperature will always be equal to or greater than the wet-bulb. This parameter is calculated from the temperature, dew point, and either sea level pressure or altimeter.
ch	High cloud type		asos	Definition: Clouds of type Cirrus, Cirrocumulus, Cirrostratus. Cirrus (Ci) - Detached clouds in the form of delicate white filaments or white or mostly white patches of narrow bands. These clouds have a fibrous appearance (hairlike), or a silky sheen, or both. Cirrocumulus (Cs) - Thin white patch, sheet , or layer of cloud without shading, composed of very small elements in the form of grains, ripples, etc., merged or separate, and more or less regularly arranged; most of the elements have an appearance width of less than one degree. Cirrostratus (Cs) - Transparent, whitish cloud veil of fibrous (hairlike) or smooth appearance, totally or partially covering the sky, and generally producing halo phenomena.
cl	Low cloud type		asos	Definition: Clouds of type Stratocumulus, Stratus, Cumulus and Cumulonimbus. Stratocumulus (Sc) - Gray or whitish patch, sheet or layer of cloud which almost always has dark pats, composed of tessellations, rounded masses, rolls, etc., which are nonfibrous, and which may or may not be merged; most of the regularly arranges small elements have an apparent width of more than 5 degrees. Stratus (St) - Generally gray cloud layer with a fairly uniform base, which may give drizzle, ice prisms, or snow grains. When the sun is visible through the cloud, its outline is clearly discernible. Stratus generally does not produce halo phenomena. Cumulus (Cu) - Detached clouds, generally dense and with sharp outline, developing vertically in the form of rising mounds, domes, or towers, of which the bulging upper part often resembles a cauliflower. The sunlit parts are mostly brilliant white; their base is relatively dark and nearly horizontal. Cumulonimbus (Cb) - Heavy, dense cloud, with considerable vertical extent, in the form of a mountain or huge towers. At least part of its upper portion is usually smooth, fibrous, or striated, and nearly always flattened; this part often spreads out in the shape of an anvil or vast plume.
cm	Middle cloud type		asos	Definition: Clouds of type Altocumulus, Altostratus and Nimbostratus. Altocumulus (Ac) - White or gray patch, sheet, or layer of cloud, generally with shading, composed of laminae, rounded masses, rolls, etc, which are sometimes partly fibrous or diffuse, and which may or may not be merged; most of the regularly arranged small elements usually have an apparent width between one and five degrees. Altostratus (As) Grayish or bluish sheet of layer of striated, fibrous, or uniform appearance, totally or partly covering the sky. And having parts thin enough to reveal the sun at least vaguely, as through ground glass. Does not show halo phenomena. Nimbostratus (Ns) - Heavy cloud layer, often dark the appearance of which is rendered diffuse by falling rain or snow, which in most cases reached the ground. It is thick enough to blot out the sun or moon.
compiled	Number of Records Compiled			For daily and monthly data retrievals, the hourly observations are grouped by day or month respectively. For daily observations, there should be 24 records compiled because there are 24 regularly scheduled obs each day. For monthly, the number of compiled records should be 24 obs per day multiplied by the number of days each month. If the number of compiled records does not match the number of calculated records that there should be, the number is highlighted in red and a percentage is shown. The percentage is the ratio of amount of data that was compiled to the amount of data that should have been compiled. The purpose of this column of data is to give an objective confidence value on the data.
cooling_dd	Cooling Degree Days		econet,asos,coop	--heating_dd
dew	Dewpoint Temperature	C	asos,raws	The dewpoint temperature is a measure of atmospheric moisture. It is the temperature to which air must be cooled in order to reach saturation (assuming air pressure and moisture content are constant).
dew10	Dewpoint Temperature	C	asos	--dew
dewavg	Average Dew Point	C		--dew
dewmax	Max Dew Point	C	asos	--dew
dewmin	Min Dew Point	C	asos	--dew
diravgwind	Avg Vector Direction of Wind		asos,econet	Winds are vectors - they are both a speed (magnitude) and direction. When averaging winds, there are several methods of analysis. One way is to use trigonometry for vector averaging, which takes into account both the wind speed and wind direction. Another method is to just simply average the wind speeds. However, a simple average of the wind directions often gives values that are not meaningful. For example, if the wind at one hour is from the north (0 degrees) at 5 mph and the next hour from the south (180 degrees) at 5 mph, the average of wind directions would be from the east (90 degrees) at 5 mph. This is not meaningful, since the wind never actually had any component from the east. In vector averaging, the north and south winds are of equal magnitude but opposite direction, producing and average wind vector of zero. This can also be confusing since it suggests the winds were not blowing over that 2 hour period. For this reason, we produce both the vector average winds and the average wind speed. Vector average winds are also called "prevailing winds".
diravgwind02	Direction of Vector Avg Wind		econet	--diravgwind
domperiod	Dominant wave period	sec	buoy
evap	Evapotranspiration Total	in	econet	Loss of water from the soil both by evaporation and by transpiration from the plants growing thereon. The instrument used is an atmometer, which provides sensor estimate evapotranspiration for a reference alfalfa crop.
fuelmoistureavg	Average Fuel Moisture	%	raws	Fuel moisture measures the amount of water held by fire fuels. The instrument uses fire sticks to emulate fire response characteristics of fire fuels to measure moisture and temperature, which are usually different from relative humidity and temperature of the air.
fueltempavg	Average Fuel Temperature	C	raws	Fuel Temperature measures the temperature of the fire fuels. The instrument uses a fire stick to emulate fire response characteristics of fire fuels to measure moisture and temperature, which are usually different from relative humidity and temperature of the air.
groundsnow	Snow on the Ground	in	asos,coop
gust	Wind Gusts	m/s	asos,econet	Wind Gust reflects the speed reached during a sudden, brief increase in the strength of the wind. According to U.S. weather observing practice, gusts are reported when the peak wind speed reaches at least 16 knots (18 mph) and the variation in wind speed between the peaks and lulls is at least 9 knots (10 mph). The duration of a gust is usually less than 20 seconds.
gust02	Wind Gust	m/s	econet	5 second maximum wind speed at 2meters
gust06	Wind Gust	m/s	econet	5 second maximum wind at 6 meters
gustavg	Average Wind Gusts	m/s	asos,econet	--gusts
gustdir	Direction of Wind Gust	degrees	asos,econet,raws
gustdir02	Direction of Wind Gust at 2 meters	degrees
gustmax	Maximum Wind Gust	m/s	asos,econet	Maximum 5 second wind reported at 10m above ground
gustmax02	Maximum Gust at 2 meters	m/s	econet	Maximum 5 second wind speed reported at 2 meters above ground
gustmaxdir	Direction of Maximum Wind Gust	degrees	econet
gustmaxdir02	Time of Maximum Gust at 2m	degrees	econet
gustmaxtime	Time of Maximum Gust	HHMM	econet	Time (hour and minute) of the maximum 5 seconds wind reported for the day
gustmaxtime02	Time of Maximum Gust at 2m	HHMM	econet
gusttime	Time of Wind Gust	HHMM
gusttime02	Time of Wind Gust at 2m	HHMM
heating_dd	Heating Degree Days		econet,asos,coop	A "degree day" is a unit of measure for recording how hot or how cold it has been over a 24-hour period. The number of degree days is determined by calculating the mean temperature for the day (max+min divided by two) and then comparing the mean temperature to a base value of 65 degrees F or whatever you wish. If the mean temperature for the day is, say, 5 degrees higher than 65, then there have been 5 cooling degree days. On the other hand, if the weather has been cool, and the mean temperature is, say, 55 degrees, then there have 10 heating degree days (65 minus 55 equals 10). It is a good way to generally keep track of how much demand there has been for energy needed for either heating or cooling buildings. The cooler (warmer) the weather, the larger the number of "heating (cooling) degree days"... and the larger the number of heating (cooling) degree days, the heavier the demand for energy needed to heat (cool) buildings. Growing degree days are calculated using the same concept. The only difference is the base temperature. Instead of using 65, one might use 60 for a particular crop.
lev1	Level 1 clouds		asos
lev2	Level 2 clouds		asos
lev3	Level 3 clouds		asos
lev4	Level 4 clouds		asos
lev5	Level 5 clouds		asos
lev6	Level 6 clouds		asos
maxt1	Max temp for past hour	C	asos
mint1	Min temp for past hour	C	asos
obscur	Obscuration		asos
owl	Observed Water Level		nos
panevap	Pan Evaporation	inches	coop	Daily pan evaporation from COOP stations
par	Photosynthetically active radiation	W/m2	econet	Photosynthetically Active Radiation is the light in the whole wavelength band from 400 nm (deep violet) to 700 nm (dark red) used by plants in photosynthesis.
paravg	Average Photosynthetically active radiation	W/m2	econet	--par
parmax	Photosynthetically Active Radiation max	W/m2	econet	--par
parmaxtime	Time of max PAR		econet
pind	Pressure Indicator		asos
precip	Hourly Precipitation	in	asos,crn,econet,raws,scan
precip24	24 Hourly Precipitation	inches
precip6	6 Hourly Precipitation
pres	Station Pressure	mb	econet	Station pressure is not the same as sea level pressure. Station pressure is the pressure that is observed at a specific elevation and is the true barometric pressure of a location. It is the pressure exerted by the atmosphere at a point as a result of gravity acting upon the "column" of air that lies directly above the point. Consequently, higher elevations above sea level experience lower pressure since there is less atmosphere on which gravity can act. Put another way, the weight of the atmosphere decreases as one increases in elevation. Consequently then, in general, for every thousand feet of elevation gain, the pressure drops about 1 inch of mercury. For example, locations near 5000 feet (about 1500 meters) above mean sea level normally have pressures on the order of 24 inches of mercury.
presavg	Average Station Pressure	mb	econet	--pres
presch	Pressure Change	mb	asos
presmax	Max Station Pressure	mb	asos	--pres
presmaxtime	Time of Max Station Pressure		econet
presmin	Min Station Pressure	mb	econet	--pres
presmintime	Time of Min Station Pressure		econet
pwl	Predicted Water Level		nos
remarks	Remarks		asos	Remarks in the METAR code are divided into two categories: 1. Automated, Manual (Augmented), Plain Language (Manual Only), 2. Additive and Automated Maintenance Data. The following describes the order in which remarks are reported. Automated, Manual, Plain Language Volcanic Eruption, Tornadic Activity (B/E_(hh)mm_LOC/DIR_(MOV)), Type of Automated Station (AO1, AO2), Peak Wind (PK_WND_dddff(f)/(hh)mm), Wind Shift (WSHFT_(hh)mm_FROPA), Tower Visibility (TWR_VIS_vvvvv), Surface Visibility (SFC_VIS_vvvvv), Variable Prevailing Visibility (VIS_vnvnvnvnvnVvxvxvxvxvx), Sector Visibility (VIS_[DIR]_vvvvv), Visibility at 2nd Location (VIS_vvvvv_[LOC], Lightning ([FREQ]_LTG[type]_[LOC]), Begin/End Pcpn (w'w'B(hh)mmE(hh)mm), Begin/End Thunderstorm (TSB(hh)mmE(hh)mm), Thunderstorm Location (TS_LOC_(MOV_DIR)), Hailstone Size (GR_[size]), Virga (VIRGA_(DIR)), Variable Ceiling Height (CIG_hnhnhnVhxhxhx), Obscurations (w'w'_[NsNsNs](hshshs), Variable Sky Condition (NsNsNs(hshshs)_V_NsNsNs), Significant Cloud Types, Ceiling Height at 2nd Location (CIG_hhh_[LOC], Pressure Rising/Falling Rapidly (PRESRR, PRESFR), Sea-Level Pressure (SLPppp or SLPNO), Aircraft Mishap (ACFT MSHP), No SPECI ReportsTaken (NOSPECI), Snow Increasing Rapidly (SNINCR_[inches-hr/inches on ground]), Other Significant Information (agency specific, e.g., LAST) Additive and Automated Maintenance Data Hourly Precipitation Amount (Prrrr), 3- and 6-Hour Precipitation Amount (6RRRR), 24-Hour Precipitation Amount (7R24R24R24R24), Snow Depth on the Ground (4/sss), Water Equivalent of Snow on Ground (933RRR), Cloud Types (8/CLCMCH), Duration of Sunshine (98mmm), Hourly Temperature and Dew point: 0.1°C (TsnT'T'T'snT'dT'dT'd), 6-Hour Maximum Temperature: 0.1°C (1snTxTxTx), 6-Hour Minimum Temperature: 0.1°C (2snTnTnTn), 24-Hour Maximum/Minimum Temperature: 0.1°C (4snTxTxTxsnTnTnTn), 3-Hour Pressure Tendency (5appp), Sensor Status Indicators: RVRNO, PWINO, PNO, FZRANO, TSNO, VISNO_LOC, CHINO_LOC, Maintenance Check Indicator: $
rh	Relative Humidity	%	asos,econet,scan	Relative humidity is the percentage ratio of the partial pressure of water vapor in the local atmosphere to the maximum potential partial pressure of water vapor that local conditions could have (given current conditions) at the time of observation. In other words, relative humidity is the ratio of the amount of water that the local atmosphere is holding to the amount that the local atmosphere could hold.
rh10	Relative Humidity	%	econet	--rh
rhavg	Average Relative Humidity		asos,crn,econet,raws,scan	--rh
rhavg10	Average Relative Humidity		econet	--rh
rhmax	Max Relative Humidity		asos,econet,scan	--rh
rhmax10	Max Relative Humidity		econet	--rh
rhmaxtime	Time of max relative humidity		econet
rhmaxtime10	Time of max relative humidity		econet
rhmin	Min Relative Humidity		asos,econet,scan	--rh
rhmin10	Min Relative Humidity	rh	econet	--rh
rhmintime	Time of min relative humidity		econet
rhmintime10	Time of min relative humidity		econet
slp	Sea Level Pressure	mb	asos,raws	This is the pressure reading most commonly used by meteorologists to track weather systems at the surface. Like altimeter setting, it is a "reduced" pressure which uses observed conditions rather than "standard" conditions to remove the effects of elevation from pressure readings. This reduction estimates the pressure that would exist at sea level at a point directly below the station using a temperature profile based on temperatures that actually exist at the station. In practice the temperature used in the reduction is a mean temperature for the preceding twelve hours. Mean sea level pressure should be used with caution at high elevations as temperatures can have a very profound effect on the reduced pressures, sometimes giving rise to fictitious pressure patterns and anomalous mean sea level pressure values.
slpavg	Average Sea Level Pressure	mb	asos	--slp
slpmax	Max Sea Level Pressure	mb	asos	--slp
slpmin	Min Sea Level Pressure	mb	asos	--slp
sm	Soil Moisture	m^3 / m^3	econet
smavg	Average Soil Moisture		econet
smmax	Max Soil Moisture	m3/m3	econet
smmaxtime	Time of max soil moisture		econet
smmin	Min Soil Moisture	m3/m3	econet
smmintime	Time of min soil moisture		econet
snow	Daily Snowfall	inches	coop	Daily accumulation of snowfall for COOP stations
snowdepth	Snow Depth		coop	Snowfall depth on ground for COOP stations.
speedavgwind	Avg Vector Speed of Wind		asos,econet,scan,nos	--diravgwind
speedavgwind02	Speed of Vector Avg Wind		econet,asos	--diravgwind
sr	Solar radiation	W/m2	econet	Solar radiation is a measurement of incoming solar energy received on a surface. The pyranometer used by the State Climate Office measures radiation in the 400 nanometer to 1100 nanometer wavelength range of the electromagnetic spectrum.
sravg	Average Solar Radiation	W/m2	crn,econet,raws	--sr
srmax	Solar radiation daily max	W/m2	econet	--sr
srmaxtime	Time of Max Solar Radiation		econet
st	Soil Temperature	C	econet
stavg	Average Soil Temperature	C	econet,raws
stmax	Max Soil Temperature	C	econet
stmaxtime	Time of max soil temperature		econet
stmin	Min Soil Temperature	C	econet
stmintime	Time of min soil temperature		econet
temp	Air Temperature	C	asos,econet,scan,nos,buoy
temp10	Air Temperature	C	econet	Instantaneous temperature at 10 meters.
tempavg	Average Temperature	C	crn,econet,raws
tempavg10	Average Temperature	C	econet
tempmax	Max Temperature	C	asos,econet,nos,buoy
tempmax10	Max Temperature	C	econet
tempmax24		C
tempmax6		C
tempMaxASOS	Max Air Temperature		asos
tempmaxtime	Time of max temp		econet
tempmaxtime10	Time of max time		econet
tempMeanASOS	Mean Air Temperature		asos
tempmin	Min Temperature	C	asos,econet,nos,buoy
tempmin10	Min Temperature	C	econet
tempmin24		C
tempmin6		C
tempMinASOS	Min Air Temperature		asos
tempmintime	Time of min temp		econet
tempmintime10	Time of min temp		econet
temporal	Date & Time			The Date/Time column gives the date and time of each observation. You may notice an "H" or "S" beside the timestamp when retrieving data from automated stations. The "H" means the observation was a regularly scheduled hourly observation; the "S" means it is a special observation. Special obs are sent when there is a large change in sea level pressure, visibility, or weather. By default, only regularly scheduled "H" obs will be shown. You can change this by unchecking the box just beneath step 2 on the previous page. For hourly datasets, you will see a date AND time of the observation. The time is always given in Eastern Standard Time. So during summer months when daylight savings is in effect, remember to add one hour to each time shown.
tide	Tide height	ft	buoy
vis	Visibility	mi	asos	Visibility is the greatest distance an object can be seen and identified. Method of Measurement: Usually a visual estimate. Report prevailing visibility - the maximum visibility common to one half or more of the horizon circle. When visibility is uniform in all directions, prevailing visibility and visibility are the same. When visibility is not uniform in all directions, determine prevailing visibility by dividing the horizon circle into sectors of visibility. Estimate the highest visibility common to one half or more of the horizon circle.
visavg	Average Visibility		asos	--vis
watereq	Water Equivalent of Snow	in	coop
wavedir	Wave direction	degrees	buoy
wavediravg	Average Wave Direction		buoy
waveht	Wave height	ft	buoy
wavehtavg	Average Wave Height		buoy
wd	Wind Direction	degrees	asos,econet
wd02	Wind Direction	degrees	econet
wd06	Wind Direction	degrees	econet	Wind direction at 6 meters
wdavg	Average Wind Direction	degrees	econet,raws
wdavg02	Average Wind Direction	degrees	econet
wdmax	Wind Direction of max wind speed	degrees	econet
wdmax02	Maximum Wind Speed (2m)	degrees	econet	Maximum 1 minute wind speed reported at 2 meter level
weather	Weather		asos	Weather includes precipitation, obscuration, well-developed dust/sand whirls, squalls, tornadic activity, sandstorms, and duststorms. Weather may be evaluated instrumentally, manually, or through a combination of instrumental and manual methods.
wetbulb	Wetbulb Temperature	C	raws	Wet-bulb temperature measures the effects of evaporative cooling on the temperature.
winddiravg	Average Wind Direction		asos,econet,raws
windsd	Wind Direction Standard Deviation	degrees	econet
windsd02	Wind Direction Standard Deviation	degrees	econet
windspavg	Average Wind Speed	m/s
windvarhi	High value of wind variance	degrees	asos
windvarlo	Low value of wind variance	degrees	asos
ws	Wind Speed	m/s	asos,econet
ws02	Wind Speed	m/s	econet
ws06	Wind Speed	m/s	econet	1 minute average wind speed at 6 meters
wsavg	Daily Average Wind Speed	m/s	crn,econet,raws
wsavg02	Average Wind Speed	m/s	econet
wsmax	Max Wind Speed	m/s	econet
wsmax02	Max Wind Speed	m/s	econet
wsmaxdir	Wind Direction of max wind speed	degrees	econet	The direction from which the maximum wind speed occurred
wsmaxdir02	Wind Direction of max wind speed	degrees	econet	--wsmaxdir
wsmaxtime	Time of max wind speed		econet
wsmaxtime02	Time of max wind speed		econet
wtemp	Water temperature	C	buoy