
For this week’s challenge, Lorna wanted to continue showcasing the ability to now use published data sources in Tableau Public, so this week was all about online authoring, something I rarely (if ever) do.
Connecting to the data source
From the link in the challenge, you need to select the Historical Tropical Cyclones data source, and then I selected Create Viz to start the build

Creating the Calculated field
We need to categorise the storms using the info in the challenge requirements, so create
Tropical Storm System
CASE [Usa Sshs]
WHEN -5 THEN ‘Unknown’
WHEN -4 THEN ‘Post-tropical’
WHEN -3 THEN ‘Miscellaneous disturbances’
WHEN -2 THEN ‘Subtropicakl’
WHEN -1 THEN ‘Tropical depression’
WHEN 0 THEN ‘Tropical storm’
WHEN 1 THEN ‘Category 1’
WHEN 2 THEN ‘Category 2’
WHEN 3 THEN ‘Category 3’
WHEN 4 THEN ‘Category 4’
WHEN 5 THEN ‘Category 5’
END
We also need to identify the start date of each storm. For this I first converted the Iso Time field into a datetime
ISO Datetime
DATETIME([Iso Time])
and then used a FIXED LOD to determine the minimum date per storm and season
Start Date per Storm
{FIXED [Name], [Season (Year)]:MIN([ISO Datetime])}
I then used this field to capture just the month per date, which is needed for the filter control.
Month, Year
DATE(DATETRUNC(‘month’,[Start Date per Storm]))
To build the map, I decided to use map layers, so created a loation point for the latitude and longitude fields provided
Point
MAKEPOINT([LAT],[LON])
Finally for the bar chart, we need a count of storms per category within the selected timeframe
#No of Storms
COUNTD([ISO Datetime])
Building the bar chart
Set Season (Year) to be a discrete dimension, then on a new sheet, add Season(Year) to filter and select 2026 from the list presented.
Then add Month,Year to Filter, select the ‘blue’ Month / Year option (middle of the list displayed)…

.. then select Select from list from the List dropdown, and select just June 2026 and July 2026

Once both fields are on the Filter shelf, set them so they both apply to all worksheets using the data source, as the same filters will be needed when the map is built.

Add Tropical Storm System to Rows and #No of Storms to Columns. Sort Tropical Storm System by the minimum of the Usa Sshs field ascending

Change the mark type to a bar and add Tropical Storm System to Colour, adjusting colour as required.

Double click into Columns and manually type MIN(1) to create a secondary axis. Move Tropical Storm System from the Colour shelf to the Label shelf on this marks cark. Change the mark type to Gantt Bar, reduce the Size and set the opacity on the colour shelf to 0.

Edit the Min(1) axis to start at 0 and end at 1. Then set the chart to dual axis (but DO NOT synchronise the axis). Set the chart to fit entire view. Hide both axis and the header column (uncheck show header)

Adjust Tooltip. The format via the Format > Worksheet menu option. Set background of worksheet to black, remove row & column dividers, turn off all gridlines, zero lines

Building the Map
On a new sheet, double click Point which should automatically generate a map, with the filters already applied.

Change the mark type to circle and add Name and ISO Datetime as a discrete exact date (blue pill) to Detail. Add Usa Wind (Kts) to Size and Tropical Storm System to Colour. Apply a sort to the Tropical Storm System field, this time to sort by Usa Sshs field descending. Adjust Tooltip to suit.

Set the background colour of the map to dark (Map > background maps menu option). Remove the halo from the marks (via the Colour shelf).

Now drag another instance of Point towards the top of the canvas, and drop when the add a marks layer option appears,to create a 2nd marks card (Point 2). Change this mark type to line and move the marks card to be beneath the one labelled Point.
Add Name to Detail and ISO Datetime as a continuous exact date (green pill) to Path. Duplicate the Usa Wind (Kts) pill to create a ‘copy’ version, and add this to Size. Having a second instance, allows the size on the 2 marks cards to vary. Adjust the size to suit so it is larger than the circle marks, and change the Colour to white. Add Tropical Storm System to Tooltip then adjust tooltip.

Add SID to the Detail shelf on both marks cards too. Format this worksheet too, to remove any row/column dividers etc.
Add both the sheets to a dashboard, using layout containers to arrange the objects. Format the dashboard to have a dark background too.
My published via is here.
Happy vizzin’!
Donna





















































































































