Why are METARs and TAFs coded?

It took a little doing but I finally found an answer to the question posed by an anonymous reader after reading this article on TAFs that I wrote on March 2, March 2012.

Why are TAFs and METARs coded in the first place? (see my article of June 16, 2014)

I literally stumbled upon the following website from the National Climatic Data Center a couple of days ago: METAR/TAF Information Page, probably written some time before July 1, 1996. This webpage provided me with a link to their Program Overview Page that I hope is at least a partial answer, based on conditions in 1996, to the question on why coding is still used: (1) METARs and TAFs are in standard use globally, at least by the majority of countries meaning a standard set of inputs for global weather models and also benefiting pilots, and (2) using plain english even in todays era of high speed computers and communications would overwhelm weather related communications infrastructure.

I am basing my response to the question on why are TAFs/METARs coded in the first place on the METAR/TAF Information-Aviation Routine Weather Report and Aerodrome Forecast Information: Program Overview Page  from the National Climatic Data Center (obtained on June 25, 2014). I hope that those of you are interested will read the entire METAR/TAF Information Program Overview. I'll be summarizing and quoting salient sections here.

On July 1, 1996 the United States adopted METAR and TAF coding, the final step in the transition to this coding. METAR and TAF coding represented a major change, replacing older coding for airport surface weather observations and terminal forecasts that dated back to the early 1950s.

The following explanation explains why the change to the standardize METAR and TAF coding was important:

The Federal Aviation Administration (FAA), which determines aviation requirements in the United States, has determined that the domestic transition to the METAR/TAF code is vital to the standardization of these reports worldwide. The National Weather Service (NWS) and Department of Defense (DOD) are complying with this requirement. The benefits of having the U.S. standardize to these new code formats are as follows. Hourly and special observations are used both as stand alone data for the sites and as inputs to global weather models for both analysis and forecasting. It is this global use of each small bit of information which drives the need for standardization. Additionally, the increase in international flights between the U.S. and other nations from more U.S. locations than ever before lends itself to developing a more "seamless" international standard for aviation. Moreover, standardization becomes vital for the general aviation community for flights from the U.S. to Canada, the Caribbean Area, and Mexico (METAR/TAF Information -- Aviation Routine Weather Report and Aerodrome Forecast Information: Program Overview accessed on June 25, 2014 from http://www.ncdc.noaa.gov/wdc/metar/index.php?name=overview).

As for why plain english is not used, the METAR/TAF Information -- Aviation Routine Weather Report and Aerodrome Forecast Information Program Overview page from the National Climatic Data Center (probably written a few months prior to July 1, 1996 when the older coding was still in use) has this to say:

Despite all the high speed computers and communications that we have today a weather code is still required but is nothing new. The current SA code has been in place for over 40 years, and the conversion to METAR is a follow-on which is not very different. As for having these products reported in a plain language format, this is not feasible. Despite the advances in today's technology, the communication circuits used for transmitting the large and diverse suite of meteorological products (radar, upper air, climatological data, forecasts, watches, warnings, outlooks, etc.) have a finite capacity. The conversion to a plain language format for thousands of domestic and international observations that are generated each hour of the day is impractical and would easily overwhelm our meteorological communication circuits. However, having now standardized to a considerable extent does allow computer programs to expand the "code" into plain language. (METAR/TAF Information -- Aviation Routine Weather Report and Aerodrome Forecast Information: Program Overview accessed on June 25, 2014 from http://www.ncdc.noaa.gov/wdc/metar/index.php?name=overview).

I suspect, but am not certain that the need for a standard international format for TAFs and METARs still exist today. As I understand it, global weather models continue to be used so I would think that the need for standardized inputs remain. And international air travels continues.

On the matter of overwhelming 1996 communications infrastructure, I am not exactly in a position to speak to whether or not the same applies in 2014.

Are there other answers to the question on why METARs and TAFs are coded that I don't know about? Perhaps. Answers that I am unaware of speaking to conditions in 2014? Perhaps. Nor am I in a position to speculate here about the rational for coding that predated the adoption of METARs and TAFs in 1996. But for now, after spending two more days earlier this week reading a variety of information on the history of aviation weather forecasting and weather forecasting, I am glad to have even a partial answer for you.

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