PlotSPCWatches

Procedure for adding SPC Watches into your Hazards Grid

March 9, 2012

Methodology

The PlotSPCWatches procedure is used to automatically take the official watch outline (WOU) product, decode the counties, watch times, and watch numbers, and plot this into the Hazards grid. Note: to run this procedure, the Hazards grid cannot be separated into temporary grids as done by SeparateHazards. If it is separated, use the MergeHazards tool to recombine the temporary grids.

When a WOU arrives from SPC, it is decoded internally, and a notification appears on all GFEs.

WOU Notification

Next, the forecast will select PlotSPCWatches from the Hazards menu.

PlotSPC Menu

The tool then plots all active watches into the Hazards grid.

Plotted Watches

If the latest WOU cancels an existing watch, you will see the watch removed. If the latest WOU replaces a portion of an existing watch, the watch will be overwritten in the grid.

If for some reason a cancellation VTEC code does not arrive for an existing watch, you may need to run SeparateHazards, delete the canceled watch grid, then run MergeHazards . To create your WCN, save your Hazard grid in GFE, publish it to official, the run the Hazard_WCN formatter in Formatter Launcher.

How It Works

The PlotSPCWatches procedure analyzes the VTEC active table and filters records.

Records currently valid (not ones from the past) from the WOU and WCN products are separated into those originating from SPC (with action codes of NEW CON EXT EXA and EXB), and those from non-SPC (all actions including EXP and CAN).
Records are then compared. Records are eliminated from the SPC list that are also in the non-SPC list. Comparisons are based on the Event Tracking Number, Geographical Zone, Phen and Sig. After this step, the SPC list should only have records that contain the NEW watch.
Records containing EXP and CAN codes are now eliminated from the non-SPC list.
The two data sets are combined and then overlapping watches are eliminated.
All existing watches are eliminated from the Hazards grid and then the calculated watches are added to the Hazards grid.

Note: The PlotSPCWatches tool only plots events that are compatible with the current GFE mode. If the GFE mode is operational, then only "X", "O", and "E" WOU/WCN events will be considered. If the GFE mode is "TEST", then only "T" WOU/WCN events will be considered.