Crazy Temp Changes in PA

Tonight I want to show you a graph of the weather conditions at my house today in Central Pennsylvania, when we had a major storm front pass through.

Our normal weather was turned upside down.

Why did the temperature rise all night but then fall suddenly this morning?

Taking small portions of the "Storm in Technicolor" image, you'll notice that to the west of the low pressure system the wind arrows are from the northwest, bringing in(or "advecting" as we say in meteorology) cold air in from Canada...

...but to the east of the storm, the wind arrows indicate wind coming up out of the south, bringing warm air from the Southeast up into Pennsylvania.

Let's recap - this is simple geometry - as the winds circulate counterclockwise around a low pressure system, if you're at the "A" on the figure below, you'll get northerly winds. If you're at the "B" you'll get southerly winds.

The latter was the situation last night when temperatures rose to incredibly warm levels here in State College, Pennsylvania. Notice on the graph below, temperatures rose from 55 to 63 degrees in a few minutes

and continued to rise all night to reach nearly 70 degrees at 7 a.m., 37 degrees above the normal low temperature! But then the West wind hit, the temperature plummeted from 64 to 47 in two hours, and the front's passing was announced.

*We've talked before about how winds can affect temperatures here in Central PA, even without a frontal passage.