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On Wednesday, April 18th, the Wasatch Front got hit with a storm that produced snowfall. I watched the winds associated with the storm blow the big flag outside my office steadily from the north. But, when I viewed the Doppler and radar maps on KSL.com's weather page, the animated maps showed that the storm was clearly moving from the south.
So my question is, how was the wind blowing the flag steadily towards the south but the weather radar showed the storm moving towards the north?
Storm direction and wind can be completely different. You can have the storm moving in from the south and the winds be out of the north, this isn't unusual.
Think about what a "storm" actually is. It's an area of low pressure. Areas of low pressure move in a counter clockwise direction. If you want to draw this on a piece of paper it might be helpful. Go head and put a big red L on a piece of paper. Then draw some counterclockwise arrows on it. Heck, I'll join in the fun here and put an image from MS paint, isn't weather great?
The winds ahead of the low blow out of the south and the winds behind it will be out of the north or northwest. You can have the low itself (the big red L) moving any which way. The whole system can move from south to north, from west to east or even from north to south.
In your example, the storms were moving north (from the south) and the winds were north on the flag. That's ok! You can have south moving storms and be on the backside of the low where the winds are from the north. So the winds around the low will make your storms moving from south to north, but the surface winds around the low are from the north.
To understand this more, go ahead and draw yourself a map of Utah, and then slap a low on there. Then draw another Utah and put the low more northeast. You see, the storms can move northeast with the low or come from the south around it, but the winds on the backside are still out of the north. Here's an image on the right.
Hopefully this will have you understanding the flow around the low. If not, just send another note and we can clear it up.
Answered by KSL Meteorologist Dina Freedman.