There’s an update for this tags system now. It fixes the issue you can get if someone arrives at your page at the same time that WD is uploading the tags file. When this happens the tags file doesn’t exist, so you get php errors, and empty spaces where your tag output should be.
The update makes sure your visitors never experience an ugly broken, page by automatically refreshing the page if the tags file is uploading at that moment.
Also I have some good news for Arnt (see below).
And I’ve just released a new tides processor script!
You can get the update, scripts and more from http://www.newtonandnoss.com/weather/tech/