ViewWCL

Procedure for viewing the SPC proposed watches

Methodology

The first step in the watch by county process occurs when the Storm Prediction Center issued a Watch Coordination List (WCL) product. This product outlines their first guess at what the watch should be, and is used a reference for the watch coordination conference call.

In GFE, the display of WCL information is handled in a two step process.

First, the WCL arrives internally, triggering a notification on all GFEs.

WCL Notification

At that point, the forecast should select ViewWCL from the Hazards Menu.

View WCL Menu

A dialog is displayed and the forecaster selects the appropriate bulletin. The dialog lists all of the WLCs received in the last six hours.

When the procedure runs, it will create a temporary grid in GFE called ProposedWatches. This grid has no bearing whatsoever on the actual Hazard grid, as it is for display and coordination only.

WCL Grid

The grid has eight labels. These are:

Key	Current Watch Type	Proposed Watch Type
SV.A	None	Severe Thunderstorm Watch
TO.A	None	Tornado Watch
sv.a	Severe Thunderstorm Watch	No Change
to.a	Tornado Watch	No Change
to->SV	Tornado Watch	Severe Thunderstorm Watch
sv->SV	Severe Thunderstorm Watch	Severe Thunderstorm Watch (New)
sv->TO	Severe Thunderstorm Watch	Tornado Watch
to->TO	Tornado Watch	Tornado Watch (New)

Here is an example of a WCL grid with two watches displayed. The brighter blue region is the new (proposed) Severe Thunderstorm Watch. The darker red area to the southeast is an existing Tornado Watch. The purple area between them are counties which are currently under the Tornado Watch, but will be under the Severe Thunderstorm Watch when it is issued.

WCL Grid 2

How It Works

The ViewWCL procedure reads in saved data written into the EDEX databases by the VTEC Decoder. The data contains the watch type, the ugc list of counties, the WCL issuance time, and the WCL expiration time. The procedure then filters the VTEC active table and extracts records that meet all of the following conditions:

Product PIL is "WCN"
Office ID is your own office id
Event ending time is later than the current time
The VTEC action code is not CAN or EXP.

The final steps are:

The procedure calculates the starting and ending time of the "to-be-created" grid by encompassing all events that were filtered, plus the issuance and expiration time.
Any existing ProposedWatches grids are removed from the GFE.
Comparisons are made between the proposed WCL watch and the active table information to determine the correct "category" for display.
The temporary ProposedWatches grid is created and displayed.