Why Did We See 70's Last Week?

We had a beautiful stretch of weather last week to start off the month of November as highs exceeded 70 degrees four straight times. It was unusual, and record high temperatures were threatened during the stretch of warmer weather. So why did we see that warmth?

Well, surprisingly enough, it starts all the way in the Gulf of Alaska. Due to the dynamics of the atmospheric circulation pattern of the Northern Hemisphere, this low pressure system is semi-permanent. With that low being there---and being strong enough--a dominant high pressure system was located right off of the Pacific Northwest coast, causing ridging--or warmer weather--to form adjacent to the West Coast.

Then, due to the properties of ridges and troughs, a trough was located immediately downstream of that high pressure system and ridge over the western half of the United States. That trough brought a period of colder weather and rainy/snowy weather to the West. And, as you would probably expect, a ridge was located over the eastern United States as the jet stream lifted north. As a result, locations from Nebraska to New Jersey witnessed temperatures well-above normal, in addition to plentiful sunshine.

The strength of that ridge allowed it to remain in place for nearly five days before a strong low pressure system was finally able to break the ridge down and bring a return to normal temperatures to the Stateline.