The list below contains explanations of the individual data elements listed above in the AFOS file NMCFWOOLM. Items marked with an asterisk (*) are not absolutely necessary. |
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Station Name (ST NME) |
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Station Number (STAT'N) |
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Current Date (DATE) |
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Hour of the Observation (HR) |
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Type of Observation (T) |
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(O) = Observed, (F) = Forecast |
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State of Weather (W) |
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A one-digit code number describing the weather at the time of the observation. |
0 |
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- Clear, less than 1/10th cloud cover |
1 |
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- Scattered clouds, 1/10-5/10 cloud cover |
2 |
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- Broken clouds, 6/10-9/10 cloud cover |
3 |
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- Overcast, 10/10 cloud cover |
4 |
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- Fog |
5 |
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- Drizzle or mist |
6 |
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- Rain |
7 |
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- Snow |
8 |
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- Showers |
9 |
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- Thunderstorms |
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Notes:
An "8" should be used when showers are in sight or occurring at the observing weather station.
Thunderstorms in progress (lightning seen or thunder heard) should be recorded by stations having unrestricted visibility (i.e., lookouts) only when the activity is not more than 30 miles away.
States of the Weather 5, 6, or 7 (i.e., drizzle, rain or snow) will set the "fuels-wet" flag to "Y", which causes key NFDRS components and indexes to be set to zero because generalized precipitation over the entire forecast area is assumed. States of Weather 8 and 9 assume localized precipitation and will not set the "fuels-wet" flag to "Y".
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Dry Bulb Temperature (DBT) |
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The observed dry bulb temperature to the nearest whole degree. |
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Humidity (RH) |
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For manual fire weather stations the traditional humidity entry is the wet bulb temperature. Relative humidity is the standard entry for RAWS stations. |
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Yesterday's LAL (Y) |
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A one-digit number that best describes the lightning situation from midnight yesterday to midnight last night. (See table below). |
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Today's Lightning Activity Level (M) |
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A one-digit code that best describes the lightning activity from midnight last night to basic observation time today. Note: This is for a 30-mile radius of the weather station. |
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1 |
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No thunderstorms or building cumulus clouds observed. |
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2 |
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Infrequent lightning. A single to a few building cumulus clouds with only an occasional one reaching thunderstorm intensity. Thunderstorms or lightning need not be observed for this activity level; however, at least on large cumulus clouds must be present. |
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3 |
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Occasional lightning (1-2 cloud-to-ground strikes per minute). Building cumulus are common; thunderstorms are widely scattered. |
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4 |
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Frequent lightning (2-3 cloud-to-ground strikes per minute). Thunderstorms are common and cover 20-30% of the sky. Lightning is primarily cloud-to-cloud or cloud-to-ground, but cloud-to ground lightning is observed. |
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5 |
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Frequent and intense lightning (cloud-to-ground strikes > 3 per minute). Thunderstorms are common, occasionally obscuring the sky. Moderate to heavy rainfall with the thunderstorms and light to moderate rainfall preceding and following the storm. Lightning of all kinds occurs frequently and is characteristically persistent during the storm. |
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6 |
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Low lightning flash rate (less than 1-3 strikes in a 5 minute period). Scattered towering clouds with a few thunderstorms. Bases of the clouds are high; virga is the most predominate form of precipitation. |
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Wind Direction* (Dir) |
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Reported either as the degrees or the alpha code from which the wind is blowing at the time of the observation. RAWS stations default to degrees. The reported values represents the 10-minute average wind directions that corresponds to the same period as the wind speed. |
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16 |
N - North |
360 |
1 |
NNE - North Northeast |
23 |
2 |
NE - Northeast |
45 |
3 |
ENE - East Northeast |
68 |
4 |
E - East |
90 |
5 |
ESE - East Southeast |
113 |
6 |
SE - Southeast |
135 |
7 |
SSE - South Southeast |
158 |
8 |
S - South |
180 |
9 |
SSW - South Southwest |
203 |
10 |
SW - Southwest |
225 |
11 |
WSW - West Southwest |
248 |
12 |
W - West |
270 |
13 |
WNW - West Northwest |
293 |
14 |
NW - Northwest |
315 |
15 |
NNW - North Northwest |
338 |
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A calm or no wind situation is identified by a "0" Wind Direction and a "0" Wind Speed. If wind direction information is not available, the field is left blank. AWind direction is not a required input parameter. |
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Wind Speed (WS) |
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The 10-minute average wind speed observed at the time of the daily observation in miles per hour. The reported values should represent the average wind speed at 20 feet above the ground or the surrounding vegetation. |
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10-hr Fuel Moisture* (10) |
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The measured moisture content of the 1/2- inch fuel moisture sticks to the nearest gram. The entry is left blank if the 10-hr fuel moisture value is unavailable; the danger -rating processor will calculate a value. The computed 10-hr fuel moisture value is a function of average temperature, humidity, and precipitation during the previous 24 hours. Computed values range from 1 to 35 percent, while measured values can range from 1 to 50 percent or higher. However, remember the moisture of extinction is 25 percent. |
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Maximum Temperature* (TMX) |
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Maximum temperature reported during the previous 24 hours. The maximum temperature cannot be lower than the dry-bulb temperature at the current observation time. If so, change the maximum temperature to the current dry-bulb temperature. |
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Minimum Temperature* (TMN) |
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Minimum temperature reported during the previous 24 hours. The minimum temperature cannot be higher than the dry-bulb temperature at the current observation time. If so, change the minimum temperature to the current dry-bulb temperature. |
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Maximum RH* (HMX) |
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Maximum relative humidity reported during the previous 24 hours. The maximum relative humidity cannot be lower than the relative humidity at the current observation time. If so, change the maximum relative humidity to the current relative humidity. |
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Minimum RH* (HMN) |
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Minimum relative humidity reported during the previous 24 hours. The minimum relative humidity cannot be higher than the relative humidity at the current observation time. If so, change the minimum relative humidity to the current relative humidity. |
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Precipitation Duration (PD) |
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The actual number of hours of precipitation during the previous 24 hours. The reported value should represent the total time fuels were exposed to rain since the last regular observation. |
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Notes:
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A "0" duration is reported when no precipitation is observed in the 24 hours since the last observation time. |
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If a Trace of precipitation is reported, the duration must equal at least one hour. |
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Precipitation duration is extremely important in the calculation of 100- and 1000-hr fuel moisture values. |
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Precipitation Amount (PPAMT) |
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The actual amount of precipitation reported during the past 24 hours up to the current observation time. Amounts less than 0.005" are reported as a trace. |
The precipitation amount is important in the daily computation of the Keetch-Bryram Drought Index (KBDI). The KBDI is reduced by one point for every 0.01 inches of precipitation. |
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Fuels Wet Flag (FW) |
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This entry indicates whether or not the fuels are wet at the observation time. The Fuels-Wet Flag is set to "Y" by the danger-rating processor if the State of Weather is 5, 6, or 7.. |
A Fuels-Wet Flag of "Y" causes the ignition component, spread component, energy release component, burning index, human- and lightning-caused occurrence indices and the fire load index to be set to zero (0). The 1-hr and 10-hr fuel moisture values are also set to 35% if no measured 10-hr fuel moisture stick value has been entered. |
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