Definition
A computer-generated forecast model produced by the National Weather Service that predicts the movement and dispersion of volcanic ash in the atmosphere following an eruption. The VAFTAD model forecasts ash concentrations at multiple flight levels over time, showing where ash clouds are expected to drift and how they will spread, allowing pilots and dispatchers to plan routes that avoid contaminated airspace.
Plain English
A weather product that shows where volcanic ash from an eruption is expected to travel and spread through the sky over the next several hours, so flights can be routed clear of it.
Context Anchor
Seen in weather planning and volcanic ash discussions, especially when an eruption could affect an IFR route or altitude.
Derivation
The name describes exactly what the model does: forecasts the transport (how ash moves with the wind) and dispersion (how it spreads out and thins) of volcanic ash. Built from plain English words; no hidden origin to unpack.
Why Pilots Care
Volcanic ash can cause rapid engine damage or failure, so pilots consult VAFTAD forecasts to identify and avoid contaminated airspace.
Grounding Statement
Picture an ash cloud leaving a volcano, then being pushed downwind and stretched out by the air around it; VAFTAD forecasts that movement and spreading.
Intuition Check
VAFTAD is not a real-time picture of exactly where every ash particle is right now. It is a forecast estimate of where the ash is expected to move and spread.
Example Sentence 1
Before departing on a route that passed near the recently erupted volcano, the dispatcher reviewed the VAFTAD forecast to confirm the planned altitude would remain clear of ash.
Example Sentence 2
During the weather briefing the forecaster noted that the latest VAFTAD run showed the ash plume moving northeast at flight level 300.