User Input Forecast
If you have obtained a nominal speed and direction from the manual track product, you can
do a manual forecast projection with the following settings:
• Use FCAST Product button clicked out.
• Speed and Direction are set manually by type-in or slide pot.
• FCAST Time is set to how far ahead you want to look.
• Valid Time displays the time at which the forecast is valid, that is, the data time of the
display plus the Forecast Time
FCAST Product Forecast
• Select Use FCAST Product.
• Select the forecast product, if any are available, from the option widget.
In this case the speed and direction are taken from the forecast product and the user input
fields are desensitized.
The FCAST algorithm in the Quick Look Window takes as input a product and a forecast
product (array of motion vectors and intensity changes).
The steps involved in the forecast are as follows:
1. An output array is created with the same projection and resolution as the input product
(for example, an input CAPPI that we want to forecast).
2. The forecast product motion vectors and intensity change array points are re-mapped
onto the output array. This re-mapping means that the input product and the forecast
product do not have to have the same projection, resolution, or range.
3. Usually there are many more output array pixels than there are grid points in the
forecast product. Therefore it is necessary to interpolate the spares motion vector and
intensity change points to each pixel point (pixel) in the output array. The result is that
each pixel of the output array has a motion vector and an intensity change associated
with it.
4. For each pixel of the output array, the motion vector is used to "look back" in time per
the selected forecast time. This "backwards displacement" vector points to a pixel in
the adjusted input product. The value of this pixel is then used for the output product
pixel.
5. The intensity changes in the output array are applied pixel-by-pixel to adjust the data
for growth and decay.
More information
‣
FCAST: Forecast (page 37)
6.16
Cross-Section (XSECT) Tool
The interactive cross-section is a good way to see storm structure and echo heights.
Chapter 6 – Quick Look Window
RESTRICTED 243
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