CheckTandTd

Introduction

The CheckTandTd procedure is intended to be a final check on the Temperature (T) and Dew Point (Td) grids. The tool checks that the following meteorological conditions are maintained throughout the forecast database:

MinT <= T <= MaxT

Td <= T

Optionally, the tool can be run to show the time and area over which the above conditions are violated.


How the Procedure Works

The CheckTandTd procedure begins by retrieving all of the MinT, MaxT, T, and Td grid inventory. These timeRanges are used later throughout the code, and allow the tool to work in any time zone. Next, each MinT grid and all T grids that correspond to the associated MinT timeRange are retrieved. Using numpy, each T grid is compared with the MinT grid to identify where T grid points are lower than the MinT grid. A temporary grid is created (named TLessThanMin) that highlights where this condition is met by flagging the grid with a value of one (1). All other points are set to zero. An example of the resulting “Highlight” grid is shown in Fig. 1. The points that are set to one (appearing red by default) are used to create an editArea, whereby a SmartTool can be called to set the T grid points to the MinT grid values where T < MinT.




Fig. 1. Example of theTLessThanMin “Highlight” grid, with grid points shaded in red where the T is less than the corresponding Minimum T.

An identical set of steps is performed on the T grids again, but in this case the MaxT grid is used for comparison, and a temporary highlight grid (named TGreaterThanMax) is created. All grid points with T greater than MaxT at the same point and time are used to make the editArea. A different SmartTool is called to set the T grid points to the MaxT grid values where T > MaxT.

Finally, a third check is performed to ensure that the Td grids are always at or below the T grid for the same point and time period. The same steps are performed as in the previous two checks, and the resulting highlight grid (TdGreaterThanT) shows where the Td grids are greater than the T grids. Anywhere/time the Td grid points are greater than the T grid, a SmartTool is called to adjust the Td to the T value.


Running the Procedure

When the Procedure is envoked, users are presented with two options: “Check Only” and “Force” (see Fig. 2). The CheckOnly option will not modify any grids. It will simply generate the respective highlight grids at times where the T or Td grids violate the meteorological checks. Forecasters may examine these grids to get a better idea of where and when the grids are inconsistent.




Fig. 2. The CheckTandTd Tool GUI.

The second option, Force, will run the set of SmartTools that maintain balance between the MinT, MaxT and T grids and between the T and Td grids. Selecting this option and running the tool will likely cause many T grids to be modified. Any grids that are locked by other forecasters will, of course, not be modified, so it is important that you make sure the entire set of T and Td grids are saved (unlocked) before running this tool.

No special configuration is required with this tool.