You are, most likely, facing very few consequences, if any. Probation officers generally do not file revocations of probation until after a couple missed UAs or hot tests. If you leave the state and miss a UA during that time, you may be risking a revocation, but it is unlikely. Much depends on the other requirements of your sentence and your probation officer. If you are communicating with them well and are up to date on all of you classes or public service, you will probably be fine. Most likely, they'll never find out if it is a brief trip. In the end, it may be more important to see your uncle for the last time than any of the consequences you are likely facing, and it may be easier to beg forgiveness for this than to ask permission.
A court order exists that precludes you from leaving the state. If you get caught, you can be put in the county jail or worse, depending on the plea that landed you on probation in the first place.
No one can recommend that you violate the law.
In no way am I offering you legal advice, and in no way has my comment created an attorney-client relationship. You are not to rely upon my note above in any way, but insted need to sit down with counsel and share all relevant facts before receiving fully-informed legal advice. If you want to be completely sure of your rights, you must sit down with an experienced criminal defense attorney to be fully aware of your rights.
You could ask the court that sentenced you to probation to allow you to travel over your PO's objections. This way you are compliant with probation and still get to see your uncle. I would recommend retaining a criminal defense attorney to make this request on your behalf.
Disclaimer: Any response is for informational purposes only and it does not constitute or create an attorney-client relationship. For additional information or a free consultation contact the Law Offices of Laurie A. Schmidt at (303) 747-4686.