This chapter prescribes procedures and practices applicable to the augmentation of automated surface observations at all FAA, FAA-contract and NF-OBS facilities. In addition, this chapter also prescribes specific differences in augmentation procedures and practices applicable to LAWRS observers, as well as tower visibility requirements. FAA guidelines applicable to the augmentation of automated surface observations are presented in paragraph 2-3, General Types of Observations. Figure 5-1, Summary of FAA Augmentation Requirements, summarizes the minimum augmentation requirements by type of facility, which were given previously in Chapter 2, Guidelines.

Once an observation has been augmented, the observer shall ensure the validity of the augmented data by deleting or changing the data as required.

In order to enter augmentation data into the automated weather observing system, the observer must be signed on. Sign on shall be in accordance with the respective automated weather observing system’s operator handbook or locally prescribed procedures. The "AUTO" tag at the beginning of the observation will be dropped when the observer signs on.

a.  Sign On/Sign Off the ASOS.

(1)  When using ASOS, several augmented events (e.g., tornadic activity, thunderstorm, or hail) automatically generate SPECI observations for the beginning and ending of the event. If one of these events is occurring at the close of augmentation coverage, it will be necessary to end the event or it will continue to be reported during the hours when there is no augmentation coverage. The observer shall end the event immediately after the last hourly METAR is transmitted before going off duty. The ending of the event will automatically generate a SPECI. The observer shall cancel this SPECI, enter the AUTO REMARK and disable the present weather (PREWX). The observer shall then sign off the automated weather observing system. This procedure will end the erroneous ending remark in the next observation.

(2)  Virga and volcanic ash are events that do not generate SPECIs. Virga is automatically deleted from the observation after the hourly METAR is transmitted. If virga continues to occur, it shall be re-entered. If volcanic ash is occurring at the close of augmentation coverage, it will be necessary to end the event or it will continue to be reported during the hours when there is no augmentation coverage. The observer shall end the event immediately after the last hourly METAR is transmitted before going off duty.

Figure 5-1. Summary of FAA Augmentation Requirements

b.  Sign On/Sign Off the AWOS. At AWOS sites, the observer shall sign on/sign off the automated weather observing system following the procedures stated in the AWOS Operator’s Instructions.

See Figure 15-1, Content of METAR/SPECI, and Figure 15-2, METAR or SPECI Code Format, in Chapter 15, Coding and Dissemination.

Except as specified in the following subsections, observing procedures for augmentation shall be the same as specified for the corresponding manual observation in chapters 7 through 14. Figure D-1, Service Standard Levels, shows elements to be augmented for each service level.

a.  Observing Tornadic Activity. The term tornadic activity shall include funnel clouds, tornadoes, and waterspouts. Observing procedures for tornadic activity are given in paragraph 11-29, Tornado, Waterspout, or Funnel Cloud. A funnel cloud, tornado, or waterspout is considered to begin at the time it is observed by the observer. A funnel cloud, tornado, or waterspout is considered to end at the time it disappears from sight.

b.  Observing Thunderstorms. Observing procedures for thunderstorms are given in paragraph 11-30, Reporting Thunderstorms, and paragraph 11-31, Beginning and/or Ending of a Thunderstorm. A thunderstorm occurrence begins when thunder is first heard, lightning is observed over the station and the local noise level is sufficient to prevent hearing thunder, or when lightning is detected by an automated sensor within ten miles of the airport. A thunderstorm is considered to end 15 minutes after the last occurrence of any of these criteria.

c.  Observing Hail. Observing procedures for hail are given in paragraph 11-32, Reporting Hail. Hail begins at the time it is first observed and ends when it is no longer falling. No intensity shall be assigned to hail, i.e., the observer shall not characterize hail as light, moderate, or heavy.

d.  Observing Volcanic Ash. Observing procedures for volcanic ash are given in paragraph 11-39, Special Procedures for Volcanic Ash. The observer shall report volcanic ash whenever it is observed at the station.

e.  Observing Virga. Virga is defined as precipitation falling from clouds but not reaching the ground. The observer shall report virga when observed. Virga is not considered to be present weather or an obscuration.

f.  Observing Tower Visibility. Observing procedures for tower visibility are given in paragraph 9-3, Visibility Standards.

a.  General Reporting Procedures. General operator procedures for recording and disseminating augmentation information are summarized in Figure 4-1, Operator Procedures for Providing Augmentation and Backup Information.

(1)  ASOS. At ASOS sites, report tornadic activity (to include funnel clouds, tornadoes, or waterspouts), thunderstorm, hail, volcanic ash, virga or tower visibility by making the appropriate entry on the operator's interface device in accordance with procedures in the ASOS Ready Reference Guide.

(2)  AWOS. At AWOS sites, all augmentation reports shall be made in the remarks of the report and shall be prefixed with the phrase WEA:. The reports shall be entered in accordance with procedures prescribed in the appropriate AWOS Operator’s Instructions or FAA-approved manufacturer's equipment manual.

b.  Reporting Procedures for Each Weather Observation Element.

(1)  Reporting Tornadic Activity. The term tornadic activity shall include funnel clouds, tornadoes, and waterspouts. These phenomena shall be reported in a SPECI observation whenever they are observed or disappear from sight. At ASOS sites, the event will continue to be reported automatically until the observer deletes the entry.

(2)  Reporting Thunderstorms. At ASOS sites, entry or deletion of a thunderstorm report shall be made. The event will continue to be reported automatically until the observer deletes the entry. A SPECI observation is generated automatically for the beginning and ending times of thunderstorms. A thunderstorm occurrence begins when thunder is first heard, when lightning is observed at the station and the local noise level is sufficient to prevent hearing thunder, or when lightning is detected by an automated sensor within ten miles of the airport. Location and direction of movement of the thunderstorm, and the location, type, and frequency of lightning should be reported, if known. LAWRS personnel are only required to annotate the beginning/ending times of thunderstorms.

(3)  Reporting Hail. At ASOS sites, entry or deletion of a hail report shall be made. The event will continue to be reported automatically until the observer deletes the entry. Hail begins when it is first observed and ends when it is no longer falling. No intensity is assigned to hail, i.e., hail shall not be characterized as light or heavy. Hail size should be reported, if known.

(4)  Reporting Volcanic Ash. VA is the standard contraction used for volcanic ash. It will be reported in the body of the report as an obscuration whenever observed. At ASOS sites, the event will continue to be reported automatically until the observer deletes the entry. A special observation is not required when volcanic ash is observed. No intensity is assigned to volcanic ash, i.e., the observer shall not characterize volcanic ash as light, moderate, or heavy. Remarks are optional, but if the volcanic eruption producing the volcanic ash is observed, it shall be entered in remarks and a special observation shall be generated.

(5)  Reporting Virga. When precipitation is observed to be falling from clouds but is not reaching the ground, the observer shall report VIRGA in remarks. There is no standard contraction used for virga. Virga is not considered to be present weather or an obstruction to vision. In remarks, VIRGA is spelled out in full. At ASOS sites, the event will continue to be reported automatically until the observer deletes the entry or until after the next hourly observation. The remark VIRGA will not be automatically kept in remarks of the observation past the next hourly observation. If virga persists, it shall be re-entered as a remark. No SPECI is required when virga is observed. No intensity is assigned to virga, i.e., the observer shall not characterize virga as light, moderate, or heavy. The direction of the virga from the site is optional.

(6)  Reporting Tower Visibility (NA LAWRS). At towered ASOS sites with a surface-based observer, a tower visibility report shall be made by notifying the surface-based observer or using the appropriate entry on the operator's interface device. Reporting of tower visibility shall be in accordance with coding and dissemination procedures specified in paragraph 15-25, Tower or Surface Visibility.

Examples of augmented weather observations for a typical condition (i.e. thunderstorm) are given in Figure 5-2, Examples of Augmented Observations, for AWOS and ASOS.

5-8. - 5-9. RESERVED