a beginning of a story

The darm stork clouds were looming in the horizon, slowly devouring what was once a patchless blue sky. Tall grey skyscrapers stretched across the city, casting a shadow amongst the citydwellers. People seemed to bustle about hurriedly, like a swarm of ants in a grass field. Everybody seemed to be unaware of the storm brewing closer towards the city. Businessmen talked on their mobile phones, consumed by their careers. Schoolkids congregated in packs outside 7/11 waiting for their friends whilst talking animatedly. The occassional tourist walked around, seemingly out of place, dressed in slightly unfashionable clothing with a look of amazement on their face.
There was only one person who seemed to notice the dark gathering mass in the distance.
Sandra flicked her jet black hair back, eyeing the cloud suspiciously. There was something strange, she thought. It just didn't feel right, yet she was unsure why. Putting on her heavy backpack, she walked towards the familiar green and orange sign. All her friends were already standing outside waiting for her, and she couldn't help but feel a little joy.
"Hey Sandra, what took you so long?" asked Tanya impatiently. "Uhh, nothing. Just late," replied Sandra.