What is that sound???

I'm chatting away on the phone with one of my dear friends from Bellingham, starting up the treadmill to get my exercise in for the day, (yes, I'm multitasking....you have to do that when you have kids =), when I hear this noise. Grady is sleeping in the crib...so its not him. The girls are in the playroom with me, although they've stopped playing and are looking at me inquisitively...so its not them. What in the world happened to my treadmill, I'm thinking? I stop walking (yes, I'm still on the phone) and listen...hmmm...great, now its broken. I pull the safety plug so it stops, yet the noise continues getting louder and quieter, louder and quieter. OK, so now I get off the phone to investigate. It's not the girls, not the treadmill, not the house alarm, not the smoke alarm. They're doing a lot of building in the neighborhood, so what? are they grinding stone??? Should I be worried? The girls are. They're following me around the house asking what the noise is and right now, I can't give them an answer. I look out the window...well, the tornado alarm is spinning and when it faces us, it seems to match the with the volume of the noise. It's a relatively nice day out. It's January. Is this really happening? Joe's not answering any of his phones, my neighbor's not home, none of the construction guys seems to be running for shelter, so why is my heart racing? Well, at least now I know what the tornado siren sounds like. If I watched any kind of TV other than Dora and the Backyardagains I might have known they were testing today. Lucky for me this was just a test because by the time I figured out what the siren was, the tornado would have been through here and on its way to the East Coast before I gathered up my babies and found shelter!