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When we get a storm in Utah, it is often preceded by a warm wind from the south. Right before the storm front hits, it seems the wind shifts to the opposite direction from the north and is considerably colder. On top of this, it appears like the clouds roll in from the west, how can this be? Is the storm actually sucking warm air toward it, or is it pushing cold air away from it?
Larry F.
***************************************************** Yet another great question from our inquisitive viewers of Utah.
To examine this Q, we need to dig deep into what cold fronts do! First of all a front is a dividing line between two different air masses, usually of different density caused by temperature differences. The front is given the name of whatever air mass is advancing, if cold air is advancing then the front is labeled a cold front and so on and so forth.
Cold fronts happen when cold air pushes up lighter warm air. The uplifting of air causes clouds and storms.
Ahead of the cold front, the winds are usually out a southerly direction, once the front rolls in, the winds shift to a northerly direction such as north or northwest, ushering cold air with it.
Frequently you can have moisture and clouds ahead of the front and more clouds or precipitation behind it too. If storms are ahead of a front, sometimes you'll get the rain first, then the wind will shift once the front passes you. It works the other way too, the storms can be behind or along the front, so the wind can shift first, then the storms can roll in. Since much of our weather systems move from west to east in this country, our clouds often roll in from the west as Larry observed. Sometimes the clouds will come in from the south and west as well as they rotate around an area of low pressure which moves counter clockwise.
Answered by KSL Meteorologist Dina Freedman
