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ADDS - Turbulence Help Page (2 of 2)
Back to Turbulence Page
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The algorithm takes as input forecasted fields from the National Centers
for Environmental Prediction (NCEP) Rapid Update Cycle (RUC-2) gridded aviation
forecast model and turbulence observations within the last 1 1/2 hours
and diagnoses Clear Air Turbulence (CAT) potential for the RUC-2 forecast
times. These forecasts are updated every 3 hours. The turbulence diagnostic
is a combination of some 23 common turbulence diagnostics or turbulence
indices (e.g., wind shear, Richardson's number, Ellrod Indices, etc.) optimized
to give the best agreement with available observations. These indices are
most useful in forecasting upper level CAT associated with mountain waves,
upper level fronts, and jet streams. The GTG results are shown here as
contour maps of predicted CAT intensity at flight levels 22,000
to 41,000 ft at 4,000 foot intevals. The prediction can be interpreted
roughly as follows:
- 0.0 - 0.125 = no turbulence
- 0.125 - 0.375 = light turbulence
- 0.375 - 0.625 = moderate turbulence
- 0.625 - 0.875 = severe turbulence
- 0.875 - 1.0 = extreme turbulence
Note: This product is still experimental and presently under
intensive evaluation. These predictions should therefore be used only with
sufficient understanding of the atmospheric processes involved and errors
inherent in their prediction. Note also this algorithm is presently intended
to identify regions of upper-level CAT only, and is not intended to predict
turbulence associated with convection and thunderstorm clouds. Future versions
will include convective turbulence forecasts as well. Comments sent to
the ADDS developers via the Feedback Page
will be forwarded to the developers of GTG.
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