The NCWF product provides 1 hour extrapolation forecast.  These forecast are best for long lived mature multi-storm systems. However, the initiation and dissipation of these systems, as well as shorter lived isolated storms, are not well forecasted at this time. Work is currently being done to incorporate satellite and model data into the system in order to improve the forecasts. 

Currently, the NCWF only provides extrapolation forecasts.

The forecast methodology is documented in the following pages.

Stratiform Filter 

The first step in determining an extrapolation forecast is to track the storm in order to obtain motion vectors.   The NCWF forecast tracks storms based on a field that is similar to the Convective Hazard Detection.  This field, referred to as the "tracking hazard field", uses a stratiform-convective partitioner to remove stratiform echo and an elliptical filter to remove storm scales that are perishable. 

The image above is the result of applying the stratiform-convective partitioner (Steiner 1985) to the VIL field. The partitioner separates stratiform and convective regions. Stratiform regions are removed based on texture and intensity.  Click on the image to toggle between the stratiform-filtered and non-stratiform-filtered data fields.

Why remove the stratiform?

  • These regions trail behind the convection moving at a slower pace and influence the speed and direction used to forecast the system (see image below for example of a large area of trailing stratiform).

Click on image to see result of running stratiform filter.

Click "Next" to go to Forecast step 2: Combining radar and lightning fields.