**GenerateCyclone Tool**

The GenerateCyclone tool creates wind grids for tropical depression
events. When a cyclone is classified as a tropical depression, The TCM
text bulletin from the Tropical Prediction Center (TPC) contains only
the forecast center and maximum sustained winds; no wind radii are
provided. The Generate Cyclone tools allows forecasters to add wind
radii thus injecting more detail to this wind forecast so that they can
create more realistic wind grids more easily.

The GenerateCyclone tool was derived from the TCMWind tool. To use it,
the forecaster must first define the location and strength of the
cyclone as a function of time in a text file. The format of the file is
very similar to the format of the TCM product. A simple example is shown
below\...

FORECAST VALID 09/0900Z 25.4N 81.7W

MAX SUSTAINED WINDS 140 KT WITH GUSTS TO 170 KT.

10 KT\...\...100NE 100SE 100SW 90NW.

20 KT\...\....90NE 90SE 90SW 90NW.

30 KT\...\....85NE 85SE 85SW 75NW.

FORECAST VALID 09/1800Z 28.2N 85.8W

MAX WIND 140 KT\...GUSTS 170 KT.

10 KT\...\...100NE 100SE 100SW 90NW.

20 KT\...\....90NE 90SE 90SW 90NW.

30 KT\...\....85NE 85SE 85SW 75NW.

There are three main parts to the text file: the valid time and
location, max sustained winds, and the radii.

Forecast Valid Time and Location

Example:

FORECAST VALID 09/0900Z 25.4N 81.7W

(valid time) (lat, lon)

The forecast valid time and location must precede the radii information.
It must contain the phrase "FORECAST VALID" followed by the time in the
format dd/hhmmZ, where dd is the day of the month, hh is the hour, mm is
the minute (this should always be 00), and the Z means that the time is
in GMT. The center location of the storm follow the time and must be in
the format "aa.aN bbb.bW", where aa.a is the latitude in degrees and
tenths north and bbb.b is the longitude in degrees and tenths west. The
"N" and the "W" are required for proper decoding of the text.

Since the month and year are optional, the tool will generally create
grids containing the cyclone within the current month. When the tool
finishes you may need to scroll the Grid Manager backward or forward in
time to view your grids since they could be plotted many days before or
after the current time window.

Max Sustained Winds

Example:

MAX SUSTAINED WINDS 140 KT WITH GUSTS TO 170 KT.

(max wind) (gust value is not used)

The Max Sustained Wind line indicates the maximum sustained winds for
the cyclone. It has the format MAX WIND xxx KT\...GUSTS yyy KT, where
xxx is the maximum sustained wind and yyy is the gusts. The maximum
sustained wind value and the latitude is used to calculate a radius of
maximum wind (RMW) and is added to the list of radii. The maximum gust
is not used by the tool.

Wind Radii

Example:

10 KT\...\...100NE 100SE 100SW 90NW.

(wind value) \...(radii in each direction in nautical miles)

The wind radii actually define the wind radii values for a specified
wind speed. It has the following format: NN KT\...\....aNE bSE cSW dNW,
where NN is the wind speed value in knots and a, b, c, and d are the
values of the radii for the northeast, southeast, southwest, and
northwest quadrants, respectively, all expressed in nautical miles. All
quadrants must be listed and all must use the standard NE, SE, SW, NW
indicators for each quadrant for the tool to work properly.

Note that unlike the TCM bulletins, you can add any wind value you want
not just 34, 50, and 64 KT, and you may enter as many wind values as you
like. However, for best results, carry the same wind values through to
the end of the forecast. For example, if you define a 25 knot radius in
the first forecast period, define a 25 knot radius for the rest of the
forecast periods as well. The code that performs the interpolation works
much better when the same wind speed values are used throughout the
forecast period.

Preparing to run the tool

Before the tool can be successfully executed, the text file containing
all of the information about the cyclone must be prepared. It\'s
recommended that a template be stored in the text database under some
product that will never be transmitted. Forecasters will edit this
template, perhaps copying in the current TCM, add radii to some of the
forecaster periods, and save the file under a different text database
product name. This new name should be used when running the
GenerateCyclone tool.

Additional data from TPC

The Tropical Prediction Center produces additional data that more
precisely predicts the radius of maximum wind and the outermost closed
isobar. The GenerateCyclone tool can ingest this this data which will
generally improve the quality of the wind grids that it produces.
However, in order to download the data from the TPC web site, you must
configure and run a set of scripts before running the GenerateCyclone
tool. These scripts download the data for you and place it in the AWIPS
text database. Once stored in the database, the tool will automatically
read the additional data and use it as part of the algorithm that
generates the cyclone wind data. Please see the appendix on page 6 for
detailed information on how to set up and run these scripts.

Once the scripts are set up, forecasters should follow these steps:

-   Run the script that downloads the additional data from TPC and store
    the data in a file.

-   Run another script to read the file and store its contents in the
    AWIPS text database under a PIL identified by the basin, cyclone
    number, and year

-   Run the GenerateCyclone tool and enter the PIL for the current
    cyclone. The tool will automatically read the additional data from
    TPC using the AWIPS text database and use the data when generating
    the wind grids.

Running the tool

The GenerateCyclone tool is invoked from the GFE by selecting from the
main menu bar: Populate-\>GenerateCyclone. A GUI menu displays
immediately and looks like the figure below.

![](media/image1.png){width="4.030555555555556in"
height="3.3743055555555554in"}

The menu allows the forecaster to enter the following information:

-   **Product ID** -- the identifier of the text product under which the
    forecaster-defined bulletin was stored.

-   **Background Model** -- the background that should be used for the
    grid. This model/forecast dataset will be used as the background and
    blended with the cyclone starting at the outer edge. A time-matching
    algorithm selects the background grid whose start time matches most
    closely in time with the start time of the cyclone grid.

-   **Number of Pie Slices** -- the number of radial pieces that will be
    generated by the tool. More pie slices will generate a smoother wind
    grid, particularly in quadrants where the radii vary greatly. The
    execution time of the tool increases as pie slices increases. For
    example, doubling the number of slices will approximately double the
    tool\'s execution time.

-   **Make Grids over Selected Time Only** -- Users should select "Yes"
    if they want the tool to run over a shorter time period than defined
    in the text bulletin. Wind grids will be generated over the grid
    manager selected time range only. Leaving the option set to "No"
    will allow the tool to run over the full time period defined in the
    bulletin. De-selecting the grid manager time range has the same
    effect as selecting "No".

-   **Decrease Wind over Land (%)** - The tool will automatically
    decrease the wind speed by this percentage where the elevation is
    greater than zero (above sea level). All areas above sea level are
    adjusted by the same percentage. Users may move the slider to the
    right to increase this value and to the left to decrease it. Note
    that the range of the slider is -20 to +50. Negative values will
    increase the wind speeds for any area above sea level.

**[APPENDIX]{.underline}**

[INSTRUCTIONS TO DOWNLOAD AND STORE ADDITIONAL CYCLONE DATA]{.underline}

The following instructions list the steps required to download
additional data from TPC and store it in the AWIPS text database. All
files are included with the distribution tar file that came with the
GenerateCyclone tool.

Assumptions: User fxa in ds1 can ssh into ls1 as LDAD with no password

prompting. If it can\'t, see your ITO or AWIPS Focal Point. Also, these

scripts are needed to run the GenerateCyclone Procedure to populate

your wind grids with TPC TCM guidance for tropical depressions where

no wind radii is provided.

1\) Edit the .csh and .pl scripts to edit your local choice for the

ldir (AWIPS Local directory where scripts reside inside AWIPS) and

rdir (LDAD Local Directory where ftp script will reside)

variables. Place all the scripts in the tar package in the AWIPS

directory (ldir).

2\) Place ftp script in the LDAD working directory (rdir).

3\) Add the following entries to your trigger table in ds1 substituting
your office ID:

MIATCMAT1 /your/awips/local/dir/tcm_2ndfile.csh MIATCMAT1

(/your/awips/local/dir same as ldir). MIATCMAT2

/your/awips/local/dir/tcm_2ndfile.csh MIATCMAT2 MIATCMAT3

/your/awips/local/dir/tcm_2ndfile.csh MIATCMAT3 MIATCMAT4

/your/awips/local/dir/tcm_2ndfile.csh MIATCMAT4 MIATCMAT5

/your/awips/local/dir/tcm_2ndfile.csh MIATCMAT5

Localize ds1 triggers (mainScript.csh -trigger) as fxa.

4\) When the TCMs are stored in the database, the script

tcm_2ndfile.csh call its companion perl script. This script decodes

from the TCM the storm number and year (AL##YYYY), where AL stands for

atlantic, \## for storm number, and YYYY year). This information is

used by the perl script to remotely run as ldad the ftp script in

ldad. The ftp script downloads from TPC ftp directory the atcf file

corresponding to the TCM triggering the script. In the case of

tropical depressions where no wind radii information is contained in

the TCM, this atcf file contains the necessary circulation information

needed by the GFE GenerateCyclone Procedure to create a depression in

the wind grids.

5\) Example: If AL##YYYY in the TCM file is AL102004, then the

corresponding atcf file is stored in the AWIPS text database as

AL102004. When you run the GenerateCyclone Procedure in GFE, you will

enter the 9 letter PIL for the TCM and AL102004 will be pulled from

the text database provided you have set up these scripts. The

procedure will call both products from the text database, decode them,

and generate the depression circulation in the grids.