Wednesday, December 20, 2017

Weather Discussion for Wednesday December 20, 2017

Normal high and low temperatures for Dec 18-Dec 25  (high/low)...Redding 55/35, Chico 56/35, Quincy 44/24, Chester 42/20, Susanville 40/22, Grass Valley 54/31, Weaverville 46/29, Mt. Shasta 43/23, Yreka 43/24, Alturas 42/16

This blog will be issued every Monday, Wednesday, and Saturday morning and updated if the weather is changing or critical or interesting weather events are occurring.

The upper level low pressure area is now moving across Southern Oregon and Northern California. The main band of light rain and snow went through last night but there will be some snow flurries over the higher elevations north and east of the valley through this afternoon.  

High pressure will be back along the coast Thursday through the weekend.   The north state will partly to mostly sunny with a few high clouds.  Daytime temperatures will be above normal with cold nights.  Gusty north winds are expected Thursday and early Friday.  

Late Monday and Tuesday another weak and relatively dry low pressure trough will move across Northern California (see map below) .  This system will bring light precipitation to the foothills and mountains with showers in the valley.   Snow levels will be 3500 to 4500 feet.  

When you look at the map below you can see that the high pressure center has moved well to the north.  However, when you look west across the Pacific you see a very weak and disorganized flow pattern this is because the southern branch of the jetstream is weak with most of the energy in the northern branch which is north of the high.  The weather pattern over the northern hemisphere is not a normal December pattern.

The Old Forecaster

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