Hurricanes package

The Hurricanes package will search the parameter file for the following lines:

Hurricanes: dir
Year: yyyy
PosErr: xy.z

• dir - is the directory where hurricane data will be stored. This parameter must be set.
• yyyy - is the year of interest. If absent, the current year is assumed.
• xy.z - is the position error for observations, in kilometers. Sometimes reports give different locations for the same storm at the same time, due to different observation methods and criteria for defining the storm center. If the difference is greater than PosErr, visky prints a warning on the terminal. If absent, the Hurricanes package uses a default of 30 km.

When the package loads, it automatically retrieves and saves the archive index (e.g. http://www.nhc.noaa.gov/archive/2001/index_text.html). It then scans the index for storm names and adds them to the Hurricane menu.

When the user selects a hurricane, visky downloads the index for the storm (e.g. http://www.nhc.noaa.gov/archive/2001/ALLISON_text.html), which is then scanned for a list of reports. Reports not in the hurricane directory are downloaded and saved there. Then all reports for the storm are made available to the reports window. The track for the selected storm is drawn on the map as a solid line with dots at each observation point (usually every three hours). The text display below the map shows information about the observation nearest the cursor.

Selecting All for the hurricane displays all hurricanes for the year. If it is late in the year, this can result in a lot of downloading.

Double clicking on an observation puts its reports into the reports window. Forecast positions from the forecast discussion are displayed as dots on the map. The right arrow key selects the next observation for the current storm. The left arrow key selects the previous one.

The goes window displays the satellite image for the chosen observation. First it looks in dir/year/images to see if the image was saved from a previous session. If the appropriate image is not there, it attempts to download one from http://goeshp.wwb.noaa.gov, which stores images for about 21 days. The view can be adjusted by dragging. While dragging, a text display at the lower left shows the cursor position. This helps put features - like the eye of the storm - at the same place in the window in sequential images. The Sector menu chooses the GEOS region, either East Coast, Hurricane Sector, West Coast, Hawaii, or Alaska (EC, HU, WC, HA, and AL, respectively). The Channel menu selects the type of image, either visible, infrared, or water vapor (VS, IR, or WV). Pressing the Lock button at the lower right prevents the image from updating, which can be useful if many images are missing.

Images are saved in directories dir/yyyy/images. There will be one directory for each year. They are never deleted. It might be wise to purge the image directories from time to time.

The Hurricane menu has the following items:

• Dot size - selects the dot size, in pixels, for observations. Choosing default sets the value to that given by the 'Widget->Default dot size' menu. The current observation is two pixels larger than the rest of the dots.
• Colors - accesses a dialog box for adjusting colors. Now refers to the current observation, its forecast dots, Track refers to the rest of the storm's track. Color selections are saved in a file named $HOME/.visky/colors/Hurricanes.tcl, which is used to set colors next time the program runs. When visky starts, it backs up this file to $HOME/.visky/colors/Hurricanes.tcl.bu, which can be used to revert to the original colors if desired.

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