Why Are Terminal Area Forecasts Amended So Frequently?

Here's how often TAFs are typically issued and when you can expect to see them altered.

Scott Dennstaedt, Ph.D

Wednesday, December 04, 2024 at 08:53 AM ET

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Edited By: tccjeremy

The TAF is one of the most difficult forecasts to make in aviation weather. [Adobe Stock]

Key Takeaways:

Terminal Area Forecasts (TAFs) are amended by NWS meteorologists when actual weather conditions, such as discrete flight categories, thunderstorms, or freezing precipitation, differ significantly from the forecast, often triggered by a "weather watch" software.
Specific amendment criteria exist for elements like wind, where significant deviations in direction (30+ degrees at 13+ knots) or speed (11+ knots when original or new speed is 13+ knots) would prompt an amendment.
The perceived increase in TAF amendments is largely due to an enhanced aviation project for high-impact airspace (e.g., Chicago, Atlanta, NYC), where TAFs are now issued on a more frequent two- or three-hour cycle instead of every six hours.
These regularly scheduled, more frequent TAF updates are labeled as "amended" forecasts ("AMD"), making it difficult for users to distinguish between an actual amendment due to criteria being met and a routine, pre-scheduled new forecast for these busy areas.

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Question: It seems like terminal area forecasts (TAFs) are amended more frequently these days. Is there a reason for this?

Answer: TAFs are issued by highly trained National Weather Service (NWS) meteorologists physically located at the 123 Weather Forecast Offices (WFOs) located throughout the U.S. and its territories. Each WFO issues a forecast for all airports serviced by a TAF within its county warning area (CWA). These areas are shown below.

Map of National Weather Service (NWS) Weather Forecast Offices (WFO) county warning areas. [Courtesy: Scott Dennstaedt]

For example, the Greenville-Spartanburg WFO in Greer, South Carolina, issues a TAF for six terminal areas to include, Charlotte Douglas International Airport (KCLT), Hickory Regional Airport (KHKY), Anderson Regional Airport (KAND), Asheville Regional Airport (KAVL), Greenville-Spartanburg International Airport (KGSP), and Greenville Downtown Airport (KGMU).