You’re right. Use no more words than necessary to make your point.
Severe weather may postpone the event.
Please be aware the event may be postponed due to severe weather.
Please be aware the event may be postponed due to (because of) the imminent, severe weather.
Please be aware the event may be postponed if there is severe weather.
Severe weather will postpone the event.
The 'Seven Cs' of Effective Communication
Clear: Your messages need to be clear if they are to be effective.
Concise: If you want your messages to be read by busy people, make them brief. Say what you need to say, and say no more (while maintaining goodwill, of course). Remove all words phrases and sentences that serve no purpose. You can also eliminate wordiness by substituting one word for wordy, overused expressions.
Concrete: You have a choice in your writing to use concrete (specific) or abstract (vague) words. They both have a place. However, concrete terms are typically more accurate and, in some cases, more believable.
Correct: Correctness in business writing includes spelling, grammar, punctuation, and format. For spelling, punctuation, and grammar, you should keep a dictionary and a writer's guide at your desk.
Coherent: Messages need to "hang together." Ideas need to flow from one to the next through smooth transitions. You can achieve this by outlining your messages, writing simple sentences and focusing each paragraph on one idea. You can also improve the coherence of your message through parallel structure, connecting words and phrases, and guide posts.
Complete: Check to be sure that your message is complete. Have you included all the information you need to ensure that the other person can do a complete job or make a reasonable decision?
Courteous: Your message should be positive-building goodwill and focused upon the reader. Watch gender specific language and always use proper titles.