Aviation Routine Weather Report (METAR)  A METAR is an observation of current surface weather  reported in a standard international format. While the  METAR code has been adopted worldwide, each country is  allowed to make modifications to the code. Normally, these  differences are minor but necessary to accommodate local  procedures or particular units of measure. This discussion of  METAR covers elements used in the United States.  METARs are issued on a regularly scheduled basis unless  significant weather changes have occurred. A special  METAR (SPECI) can be issued at any time between routine  METAR reports.  Example:  METAR KGGG 161753Z AUTO 14021G26KT 3/4SM  +TSRA BR BKN008 OVC012CB 18/17 A2970 RMK  PRESFR  A typical METAR report contains the following information  in sequential order:  1. Type of report—there are two types of METAR  reports. The first is the routine METAR report that is  transmitted on a regular time interval. The second is  the aviation selected SPECI. This is a special report  that can be given at any time to update the METAR for  rapidly changing weather conditions, aircraft mishaps,  or other critical information.  2. Station identifier—a four-letter code as established by  the International Civil Aviation Organization (ICAO).  In the 48 contiguous states, a unique three-letter  identifier is preceded by the letter “K.” For example,  Gregg County Airport in Longview, Texas, is  identified by the letters “KGGG,” K being the country  designation and GGG being the airport identifier.  In other regions of the world, including Alaska and  Hawaii, the first two letters of the four-letter ICAO  identifier indicate the region, country, or state. Alaska  identifiers always begin with the letters “PA” and  Hawaii identifiers always begin with the letters “PH.”  Station identifiers can be found by calling the FSS, a  NWS office, or by searching various websites such  as DUATS and NOAA's Aviation Weather Aviation  Digital Data Services (ADDS).  3. Date and time of report—depicted in a six-digit group  (161753Z). The first two digits are the date. The last  four digits are the time of the METAR/SPECI, which  is always given in coordinated universal time (UTC).  A “Z” is appended to the end of the time to denote  the time is given in Zulu time (UTC) as opposed to  local time.  7. Weather—can be broken down into two different  categories: qualifiers and weather phenomenon  (+TSRA BR). First, the qualifiers of intensity,  proximity, and the descriptor of the weather are given.  The intensity may be light (–), moderate ( ), or heavy  (+). Proximity only depicts weather phenomena that  are in the airport vicinity. The notation “VC” indicates  a specific weather phenomenon is in the vicinity  of five to ten miles from the airport. Descriptors  are used to describe certain types of precipitation  and obscurations. Weather phenomena may be  reported as being precipitation, obscurations, and  other phenomena, such as squalls or funnel clouds.  6. Visibility—the prevailing visibility (¾ SM) is reported  in statute miles as denoted by the letters “SM.” It is  reported in both miles and fractions of miles. At times,  runway visual range (RVR) is reported following the  prevailing visibility. RVR is the distance a pilot can  see down the runway in a moving aircraft. When RVR  is reported, it is shown with an R, then the runway  number followed by a slant, then the visual range  in feet. For example, when the RVR is reported as  R17L/1400FT, it translates to a visual range of 1,400  feet on runway 17 left.  5. Wind—reported with five digits (14021KT) unless  the speed is greater than 99 knots, in which case the  wind is reported with six digits. The first three digits  indicate the direction the true wind is blowing from in  tens of degrees. If the wind is variable, it is reported  as “VRB.” The last two digits indicate the speed of  the wind in knots unless the wind is greater than 99  knots, in which case it is indicated by three digits. If  the winds are gusting, the letter “G” follows the wind  speed (G26KT). After the letter “G,” the peak gust  recorded is provided. If the wind direction varies more  than 60° and the wind speed is greater than six knots,  a separate group of numbers, separated by a “V,” will  indicate the extremes of the wind directions.  4. Modifier—denotes that the METAR/SPECI came from  an automated source or that the report was corrected. If  the notation “AUTO” is listed in the METAR/SPECI,  the report came from an automated source. It also lists  “AO1” (for no precipitation discriminator) or “AO2”  (with precipitation discriminator) in the “Remarks”  section to indicate the type of precipitation sensors  employed at the automated station.  When the modifier “COR” is used, it identifies a  corrected report sent out to replace an earlier report  that contained an error (for example: METAR KGGG  161753Z COR).  13-6 