Try these:

First go to Application Manager(the default one), go to Menu->Application Catalogues and check if "Nokia Applications" catalogue is Enabled.

Then go to Update section and leave the phone for 5 minutes until catalogues are updated and H.A.M. checks applications are up-to-date. Update if you have any updates available.

Close App. Manager and open X Terminal
type:

If that works you are good to go. If not:
Go to App. Manager and install rootsh, sudser and then Foreca Weather/Foreca Weather.