earth science

Terminal aerodrome forecast

Terminal aerodrome forecast is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Terminal aerodrome forecast rather than just read about it. In short: In meteorology and aviation, terminal aerodrome forecast (TAF) is a format for reporting weather forecast information, particularly as it relates to aviation. TAFs complement and use similar encoding to METAR reports.

Key takeaways

Terminal aerodrome forecast belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Terminal aerodrome forecast to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Terminal aerodrome forecast from memory before moving on to harder problems.

Reference excerpt

In meteorology and aviation, terminal aerodrome forecast (TAF) is a format for reporting weather forecast information, particularly as it relates to aviation. TAFs complement and use similar encoding to METAR reports. They are produced by a human forecaster based on the ground. For this reason, there are considerably fewer TAF locations than there are airports for which METARs are available. TAFs can be more accurate than numerical weather forecasts, since they take into account local, small-scale, geographic effects. Today, according to the advancement of technology in civil aviation, the TAF is sent as IWXXM model.

Issuance, amendment and cancellation In the United States, TAFs are issued for nearly 700 airports. Most of them provide a 24-hour forecast for the airport, with some major airports forecasting for 30 hours into the future. TAFs are issued at least four times a day, every six hours, for major civil airfields: 0000, 0600, 1200 and 1800 UTC, and generally apply to a 24- or 30-hour period, and an area within approximately five statute miles (8.0 km) (or 5 nautical miles (9.3 km) in Canada) from the center of an airport runway complex. TAFs are issued every three hours for military airfields and some civil airfields and cover a period ranging from 3 hours to 30 hours. Different countries use different change criteria for their weather groups. In the United Kingdom, TAFs for military airfields use colour states as one of the change criteria. Civil airfields in the UK use slightly different criteria. If information sources, such as surface observations, are missing, unreliable, or not complete, forecasters will append AMD NOT SKED to the end of a TAF. This code indicates the forecaster has enough data, using the total observation concept, to issue a forecast, but will not provide updates. This allows airport operations to continue using a valid TAF. In rare situations where observations have been missing for extended periods of time (i.e., more than one TAF cycle of 6 hours) and the total observation concept cannot provide sufficient information, the TAF may be suspended by the use of NIL TAF.

Responsible agencies In the United States, the weather forecasters responsible for the TAFs in their respective areas are located within one of the 122 Weather Forecast Offices operated by the United States' National Weather Service. In contrast, a trend type forecast (TTF), which is similar to a TAF, is always produced by a person on-site where the TTF applies. In the United Kingdom, most TAFs for military airfields are produced locally, however TAFs for civil airfields are produced at the Met Office headquarters in Exeter. The United States Air Force employs active duty enlisted personnel as TAF writers. Air Force weather personnel are responsible for providing weather support for all Air Force and Army operations.

Code This TAF example of a 30-hour TAF was released on November 5, 2008, at 1730 UTC:

TAF KXYZ 051730Z 0518/0624 31008KT 3SM -SHRA BKN020 FM052300 30006KT 5SM -SHRA OVC030 PROB30 0604/0606 VRB20G35KT 1SM TSRA BKN015CB FM060600 25010KT 4SM -SHRA OVC050 TEMPO 0608/0611 2SM -SHRA OVC030 RMK NXT FCST BY 00Z= The first line contains identification and validity times.

TAF indicates that the following is a terminal aerodrome forecast. This line may also indicate an amended forecast (TAF AMD) or a corrected forecast (TAF COR) KXYZ indicates the airport to which the forecast applies (ICAO airport code). 051730Z indicates that the report was issued on the 5th of the month at 1730 UTC (also known as Zulu, hence the Z). 0518/0624 indicates that the report is valid from the 5th at 1800 UTC until the 6th at 2400 UTC. The remainder of the first line contain the initial forecast conditions. Variations of the codes used for various weather conditions are many.

31008KT indicates that the wind will be from 310° true at 8 knots (9 mph; 4 m/s). 3SM -SHRA BKN020 indicates that visibility will be 3 statute miles (5 km) in light (-) showers (SH) of rain (RA), with a broken ceiling (between 5⁄8 and 7⁄8 of the sky covered) at 2,000 feet (600 m) above ground level (AGL). Each line beginning with FM indicates a rapid change in the weather over a period of less than an hour.

FM052300 indicates the next period lasts from (FM) the 5th at 2300 UTC to the 6th at 0600 UTC (the effective time on the next FM line). The remainder of the line has similar formatting to the other forecast lines: 30006KT wind from 300° at 6 knots (11 km/h; 6.9 mph), 5SM visibility 5 statute miles (8 km), -SHRA light rain showers, OVC030 overcast at 3,000 feet (900 m). PROB30 indicates a 30% probability of the following temporary conditions on the 6th between 0400 UTC and 0600 UTC: VRB20G35KT wind of variable direction at 20 knots (35 km/h; 25 mph) with gusts up to 35 knots (65 km/h; 40 mph), 1SM visibility 1 statute mile (1.6 km), TSRA thunderstorms and rain, BKN015CB broken cumulonimbus clouds at 1,500 feet (450 m). FM060600 indicates that the next period lasts from the 6th at 0600 UTC until 2400 UTC (the end of the forecast period, as there is no following FM): 25010KT wind from 250° at 10 knots (20 km/h; 10 mph), 4SM visibility 4 statute miles (6.5 km), -SHRA light rain showers, OVC050 overcast at 5,000 feet (1,500 m). TEMPO means that these conditions are temporarily replaced, for periods up to 50% of the time, lasting up to 1 hour for each occurrence, between 0800 UTC and 1100 UTC with: 2SM visibility 2 statute miles (3 km), -SHRA light rain showers, OVC030 overcast at 3,000 feet (900 m). (The wind speed remains the same, as it is not mentioned.) The final line is for errata, comments, and remarks.

RMK NXT FCST BY 00Z indicates a remark that the next forecast will be issued by 0000 UTC.

See also Area forecast IWXXM METAR Pilot report Trend type forecast

References

External links Online TAF Decoder CheckWX Raw and decoded TAFs, trends and graphs searchable by location. IWXXM 1.0 Official WMO/ICAO representation of TAF information in XML

Worked examples

Example 1 — a first encounter with Terminal aerodrome forecast

Start with the simplest possible case. Write down what Terminal aerodrome forecast claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Terminal aerodrome forecast before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Terminal aerodrome forecast ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Terminal aerodrome forecast

In research: Terminal aerodrome forecast appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Terminal aerodrome forecast in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Terminal aerodrome forecast is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aviation meteorology, Meteorological data and networks, Weather forecasting, so understanding it makes those chapters shorter.
In everyday life: Look for Terminal aerodrome forecast outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Terminal aerodrome forecast in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Terminal aerodrome forecast means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Terminal aerodrome forecast out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Terminal aerodrome forecast in simple terms?

Why does Terminal aerodrome forecast matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Terminal aerodrome forecast?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Terminal aerodrome forecast.