PlotTPCEvents

Procedure to put the current tropical hazards into the Hazards grid

March 9, 2012

Methodology
How It Works

NOTE: Due to policy changes (effective 2007 tropical season) in the TCV in that the TCV only covers coastal zones, the PlotTPCEvents now only clears and sets values in the Hazard grids for coastal zones. Values created by the forecaster in the marine zones will not be modified by the PlotTPCEvents procedure. No Event Tracking Numbers are set in the Hazards grid since ETNs for tropical events now follow WFO numbering.

Methodology

The PlotTPCEvents procedure is used to automatically decode the Tropical Prediction Center TCV product, and plot the resulting data in the GFE Hazard Grid. 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 TCV arrives from TPC, it is decoded internally, and a notification appears on all GFEs.

TPC Notification

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

TPC Menu

The procedure then plots all active tropical watches/warnings into the Hazards grid.

TPC Output Grid

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

If for some reason a cancellation VTEC code does not arrive for an existing tropical event, you may need to run SeparateHazards, delete the canceled hazard then run MergeHazards.

The TCV product and the PlotTCVEvents procedure only contain coastal zone events. The forecaster is responsible for adding the appropriate marine tropical events and inland tropical events to the Hazards grid. PlotTCVEvents will only remove coastal zone events and not inland or marine events.

How It Works

This procedure is based on the TCV product events that have been captured into the VTEC Decoder. The procedure performs the following steps:

Reads the vtec active table.
Filters out all non-tropical hazards.
Filters out records from non KNHC (TPC).
Creates a list of zones for each tropical phenomena and significance for both active events (VTEC action is NEW, CON, EXA) and cancelled events (VTEC action is EXP, CAN).

Once the correct set of events have been determined, any existing tropical hazards in the Hazards grid that are found in the cancelled event list are removed. Then the calculated events are added to the Hazards grid.

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