I can honestly say I have never called in a report that I was not certain of. However, I have experienced at least one situation where I wished I had - but luckily nobody was hurt.
It happened this summer near Mound, MN (in the NW part of the Minneapolis/St Paul metro area). It was during one of those fun 'cap busts' that happened this year. Just as we were about to call it quits on what was supposed to be a big day but with no action we noticed a storm starting to break the cap about 45 miles NW of us as the day was coming to a close (we could see the tower going up but nothing was on radar at this point). We decided to go after it and hoped we would have enough daylight. We caught the storm just as it was really starting to get its act together about 30 miles or so west of the Twin Cities. The storm slowly drifted east/northeast and kept getting stronger and stronger. As it approached the western suburbs of the Twin Cities our radar was showing a well developed hook and some good rotation - yet no tornado warning, not even a severe thunderstorm warning (maybe the NWS called it quits on the day too I don't know but I found it odd there was no warning of any kind - no disrespect to the NWS intended as they are normally very good). We continued to chase the storm as it moved into the northwest suburbs of the Twin Cities. Unfortunately, we ran in to some 'less then favorable' chase terrain with many trees, hills, lakes etc. As we entered Mound, MN we noticed what appeared to be a possible wall cloud and funnel just to our north/northwest but our view was fairly obstructed so we decided to head north to check it out. To our dismay just as we got north of town a tornado touched down literally right in front of us (it was crazy and scary to see several tornado vortices spin up no more then 10 yards from the hood of our vehicle and then move east and flatten trees just east of the road that we were traveling on). Again, at this point there was no warnings of any kind so we called it in as quickly as possible (the dispatcher reported nobody else had called it in and thankfully was very quick to sound the sirens). We continued to chase the tornado as much as we could but soon lost it when we hit some more lakes and winding roads. It was a crazy situation as we even came across several joggers who were out and about as the tornado passed by them no more then 50 yards to the north of them (of course we yelled at these people to take cover as we drove by them - I will never forget the terrified looks on their faces as they realized the danger they were in).
Anyhow, long story short I still kind of wish I would have trusted my hunch and called in the storm sooner. Despite the fact that numerous houses were damaged by the tornado, nobody was injured so all in all things turned out okay I suppose...
