Aviation Weather
Not sure about how to decode METAR data? Look below.
Decoding METARs
While METAR data looks confusing, it is not difficult to decode. Consider the following example:
KLIT 200953Z 00000KT 4SM -RA BR OVC030 07/05 A3013 RMK AO2 SLP205
1. Station...in this case "KLIT" or Little Rock National Airport. 
2. Date/Time of Observation...in this case "200953Z"  
Note: The first 2 numbers represent the day of the month, with the last 4 numbers representing the Z-time. 
3. Wind Speed/Direction...in this case "00000KT"  
Note: The first 3 numbers represent the wind direction. "360" is NORTH, "090" is EAST, "180" is SOUTH and "270" is WEST. The last 2 numbers represent the wind speed in knots. To go from knots to MPH, multiply by 1.15. "00000" means that the wind is CALM.
4. Visibility...in this case "4SM"   
Note: The visibility is in "SM" or STATUTE MILES. If the visibility is 7 or higher, there are no visibility restrictions. If the visibility is less than 7 miles, something is restricting the visibility such as precipitation or an obscuration.

Visibility Restriction (Precipitation):  Precipitation may come in several forms, with the most common including DZ (drizzle), RA (rain), SN (snow), PL (sleet), GS (small hail), GR (larger hail), or UP (unknown precipitation). The precipitation may have a descriptor such as TS (thunderstorm...usually combined with RA), SH (shower...usually combined with RA) and FZ (freezing...usually combined with RA or DZ).  Precipitation intensities include - (light), no sign (moderate) and + (heavy).

Visibility Restriction (Obscuration):  Obscurations, like precipitation, come in several forms, with the most common including BR (mist...greater than or equal to 5/8SM), FG (fog...less than 5/8SM), HZ (haze) and FU (smoke).

5. Sky Condition...in this case "OVC030"   
Note: The first three letters indicate cloud coverage in eighths. 0/8 is SKC or CLR (clear), 1/8 and 2/8 is FEW (few clouds), 3/8 and 4/8 is SCT (scattered), 5/8 through 7/8 is BKN (broken) and 8/8 is OVC (overcast). The next three numbers indicate the height of the clouds in hundreds of feet. Example: "OVC030" means overcast at 3,000 feet. 
6. Temperature/Dewpoint...in this case "07/05"   
Note: The first two numbers represent the temperature in celsius. The second two numbers following the slant (/) represent the dewpoint in celsius. If the numbers happen to be preceded by an "M", that is a below zero celsius reading (example: "M05" means MINUS 5 celsius). To convert celsius to fahrenheit, or to determine the relative humidity, use a meteorological calculator
7. Altimeter...in this case "A3013"
Note: The "A" stands for ALTIMETER with the next 4 numbers representing the pressure in inches (example: "3013" means 30.13 inches). 
8. Remarks...in this case "AO2 SLP205"
Note: The remarks section of an observation may have a variety of data. The most common remarks include "AO2" indicating an ASOS (Automated Surface Observing System) observation and SLP indicating sea level pressure in millibars (example: "SLP205" means a sea level pressure of 1020.5 millibars).  

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