Is it safe to burn this many calories in a day?

I am giving my weight loss efforts a little extra push in preparation for a friend's wedding next month. I am female, 5'5", lately my Weight Watchers plan has me eating around 1400 calories a day. I have been exercising moderately for years, and want to bump up my exercise to 40 minutes of weights and 1 hr 20 mins. of vigorous cardio (elliptical) per day, with one day off per week. According to caloriesperhour.com, I would be burning 3527 calories a day if I do that (but sit at my desk or watch TV the rest of the day). It sounds like a ridiculously high amount burned, but at any rate, is it safe to burn so many extra calories a day? Please mention if you are a trainer or nutritionist or anything like that.