I tried "New York", "New York City", "10128", and "http://www.weather.com/weather/local/10128?lswe=10128&lwsa=WeatherLocalUndeclared&from=whatwhere" but I can't add my city.
The error message doesn't offer any details. I don't know if it's some kind of communications failure (doubtful) or unexpected communication from the server. Perhaps weather.com changed its URL structure?
The FAQ says to file a bug report, so that's what I'm doing.
I'm using Meterologist 1.4.4 and Mac OS X 10.4.8.
Logged In: YES
user_id=1790272
Originator: NO
A temporary workaround for this problem exists.
This bug has been marked a duplicate of bug #1718271 in an effort to clean up the bug system. The meta bug report (http://sourceforge.net/tracker/index.php?func=detail&aid=1718271&group_id=78571&atid=553756) contains links to fixes.