This should have been simple. A client's site is required to display current weather observation data retrieved via XML from w1.weather.gov. My solution was to use the on-demand features of FeedMe in a twig template to accomplish this.
As it turns out, weather.gov recently began requiring inclusion of a user agent string in the header to identify the requestor of any XML feed. If no user agent string is present, it returns error 403.
Is it possible to configure Craft or FeedMe to send a custom user agent string in all GET requests for external data?