Satellite loops are essential in tracking weather phenomena. Forecasters use them, and you can too.

Imagine you live in Meridian, MS (marked by an X). It is currently noon (1700 UTC) and 26ºC ( 80ºF). A radio broadcaster says a cold front will move across your area later today dropping temperatures into the 50s. You plan to attend an outdoor sporting event at 4:00 P.M. (2100 UTC) and must decide whether to pack more clothing than the shorts you are currently wearing. Your clothing decision depends on when the cold front will arrive: before, during, or after the game, which will be played from 4-6 P.M. (2100-2300 UTC). You decide to use satellite imagery to estimate the front’s time of arrival.

To determine when the cold front may arrive, look at the satellite imagery from the morning to see how fast the front has been moving. The blue line on the first image represents the cold front’s location at 8 A.M. (1300 UTC) while the blue line on the last image represents the cold front’s location at 11 A.M. (1600 UTC). As you can see, it has taken three hours for the front to travel approximately 97 km (60 miles) (as measured by a perpendicular line between the front’s positions at 8 A.M. and 11 A.M.). The front’s average speed has been 32 km/hr (20 mph), calculated by dividing distance by time: (97 km)/(3 hours) or (60 miles)/(3 hours).

Question: You live 178 km (110 miles) from the 11 A.M. (1600 UTC) position of the front. When do you think the front will arrive?
Before the game      During the game      After the game