One of my favorite Seinfeld episodes is The Opposite, in which George Costanza realizes that every instinct he has ever had is wrong, and vows to do the opposite, with grand results.
I often tell students, especially those who are used to the meteorology of the eastern United States, to take such advice to heart. Often, the weather here works in ways that counter your every instinct.
Tonight and tomorrow offer a straightforward example. The NAM forecast for midnight tonight shows that the flow over Utah is from the south at the surface and 700-mb. Instinct says it must be bringing in warm air right?
Wrong Costanza, do the opposite! This is a situation where cold air pushed southward off the California coast the past couple of days and will swing into Utah from the southwest tonight and tomorrow. As a result, that southerly flow is bringing in cold air.
And, it will give us a changeable day tomorrow with the fast moving system giving us a few inches of snow in the mountains tomorrow.
So, sometimes in meteorology you need to do the opposite, or at least avoid generalizations that are bound to break down when Mother Nature throws a curveball.