We have some big swings coming our way weatherwise. Saturday will bring mostly sunny skies and warm temperatures (highs in the lower 60s in Reno) before a cold front drops in Sunday, bringing gusty winds, cooler temperatures and a chance of rain turning to snow.  Scattered snow accompanies even colder temperatures on President’s Day Monday with the high barely clearing the freezing mark. Conditions dry out Monday afternoon and Tuesday, but temperatures remain very cold through the first half of the week.

hadley ferrel polar cells

We’ve been talking about the jet stream. And even though we often talk of the jet stream as a single entity, there are really four of them typically circling the globe. There’s a polar and a sub-tropical jet stream in each hemisphere, each generally following a sinuous path from the west to the east. The polar jets are lower in the atmosphere (generally 25-35,000’ altitude vs. 35-60,000’ for sub-tropical jets), and they tend to be stronger in the winter when the contrast of the polar and tropical airmasses is the greatest.

low level jet stream

And at times you can get other types of jet streams, including one in the summer that goes the opposite direction (east to west) down in the tropics, and low-level jet streams can affect the strength of winter storms hitting the west coast. That’s one kind of jet stream on which the land does have a large effect.

 

Advertisements