Thanks to stagnant air in western Nevada, the burn code is Red for Saturday (burning is prohibited). With the approach of a weak cold front from the north, I expect the air quality should improve a bit over the weekend. Variable amounts of cloudiness will move in and out for the next few days with temperatures staying in the 50s through the middle of next week. Conditions at midnight Sunday should be relatively mild with a few clouds, light winds and a downtown Reno temperature in the mid-30s.

A couple of weak to moderate storm systems do come into the region by the middle of next week, giving us a chance of finally breaking up our latest dry stretch.

500 mb

500 mb chart valid Wednesday, Dec 27 4 pm PST

So why should cold weather east result in warm weather here? First take a look at how the wind flows around the globe at our latitudes. Even though it takes a generally west to east direction, it wiggles north and south on its way in a series of waves, dipping south under the lows, and climbing north over the highs. Typically, there are 4 or 5 of these pairs, or “couplets”, of waves going around the earth at any one time.  Watch the next time you see a satellite picture and you will probably see one of these couplets.

nat sat

The upshot of all this is if you have cold air plunging into the eastern half of the country, digging a deep low, you will also pump up a strong high on either side of it, leaving us high and dry (and warm) here in the west. The stronger the eastern low, the stronger the western high.

The same concept works for precipitation. Lows bring rain and snow (notice no one is complaining about a drought in the east this winter), and highs bring generally dry weather.