Weather Discussion for Monday, Nov. 22, 2010

***ANOTHER COLD STORM TO MOVE THROUGH LATER TODAY

***HARD FREEZE IN THE SACRAMENTO VALLEY TUESDAY AND WEDNESDAY NIGHTS***
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***BRIEF EXPLANATION OF SACRAMENTO VALLEY MINIMUM TEMPERATURES***

***Some areas of the Sacramento Valley will reach near record minimum temperatures for this time of year, Tuesday night and Wednesday morning.  Because there will be light north winds the temperatures will vary quite a bit over short distances.  Here is a brief, and very general, explanation of how the temperatures vary in the valley.

In the Redding area the coldest temperatures are usually in the low lying wind sheltered areas which are the Palo Cedro and Millville areas and some areas around Anderson and Cottonwood.  The westside of town above 600 feet will be in a strong thermal belt and sometimes can be 10 to 12 degrees warmer than the airport.  Further down the valley the north wind will usually stay along and west of I-5.  This will keep the Orland area warmer than areas to the east.  The coldest areas in the valley are the Hamiltion City, Chico, and Biggs areas, where the winds are usually calm or very light.  The flow out of the Feather River canyon helps keep Oroville a little warmer and there is also a strong thermal belt on the eastside of Oroville just above the town.****
***TODAY’S WEATHER DISCUSSION**** One more cold low pressure trough is dropping southward toward our area.  This morning’s satellite picture shows this system in western Canada.  You can see that it is hooking off the coast and this will allow it to pickup more moisture.  This system will move through northern California tonight and early Tuesday.  Because it is coming in from the north most of the precipitation with it will be over the northern mountains and the Sierra/Cascade area.  Only light rain is expected in the north end of the valley and just isolated showers in the valley south of Red Bluff.  Snow levels will continue low, probably 1,000 to 1,500 feet in the north and 2,000 to 2,500 feet to the south in Plumas County.

I don’t think there is enough cold air trapped in the north end of the valley to bring the snow into Redding area, other than a few flakes near the end of the storm.  The storm will be east of our area by Tuesday afternoon, but as the map below for Wednesday shows, the jetstream will still be funneling very cold air into northern California.

Tuesday and Wednesday the north state will have a “continental polar” airmass over it.  This type of airmass is cold and very dry, so when the sun sets the temperatures will drop rapidly.  Low lying and wind sheltered areas of the north state will be very cold Tuesday and Wednesday nights.  In the Sacramento Valley, some areas will be as low as 22 to 25 degrees.  The airmass will be dry, so Wednesday will be sunny with temperatures below normal.   The high pressure area will move over the state on Thanksgiving day for sunny skies and warmer temperatures.  The next low pressure trough will reach the coast late Friday and should bring rain and snow to the area Saturday and early Sunday.
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Weather Outlook for Redding, Shasta Lake City, Anderson, Cottonwood, and Red Bluff Today:  Increasing clouds with rain by late afternoon.  Max temps 44 to 49.  South wind 10 to 20 mph in the afternoon.  Tonight: Cloudy with light rain … light snow is possible in the Shasta Lake area around sunrise.  Min temps 34 to 39.  Light wind. Tuesday: Rain ending in the morning with clearing skies.  Max temps 44 to 49  North wind 10 to 20 mph.  Tuesday Night: Clear.  Min temps 24 to 30 wind sheltered areas and 33 to 39 windy areas and westside thermal belt areas.  Wind north 4 to 8 mph.  Wednesday: Sunny.  Max temps 51 to 56.  North wind 12 to 22 mph.  Wednesday Night: Clear.  Min temps 25 to 30 wind sheltered areas and 33 to 39 windy areas and westside thermal belt areas.  Light north wind.  Thursday: Sunny.  Max temps 58 to 63.  North wind 8 to 15 mph.  Thursday Night: Clear.  Min temps 31 to 40.  Light wind. Friday: Increasing clouds in the afternoon.  Max temps 57 to 62.  South wind 8 to 18 mph.  Friday Night: Cloudy.  Min temps 41 to 47.  South wind 6 to 12 mph. Saturday: Cloudy with rain.  Max temps 45 to 50.  South wind 12 to 22 mph.  Saturday Night: Cloudy with rain.  Min temps 40 to 45.  Southwest wind 5 to 15 mph. Sunday: Cloudy with occasional showers.  Max temps 47 to 52.  Southwest to northwest wind 5 to 15 mph.  Sunday Night: Partly cloudy.  Min temps 34 to 42.  Light wind.
–The Old Forecaster

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Chris Fontana –a.k.a. “the Old Forecaster,” started his career as a meteorologist with the National Weather Service (NWS) in Sacramento. After four years as a weather officer in the USAF he transferred to the NWS office in Redding. He was the meteorologist in charge of the Redding office from 1976 until it closed in 1996. From 1996 until his retirement in 2005 he was the meteorologist in charge of the USFS Predictive Service Unit. Chris and his wife Jane have been married over 40 years and he works as a window covering installer in her business, Westwood Window Coverings.

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Chris Fontana
-- a.k.a. "the Old Forecaster" -- started his career as a meteorologist with the National Weather Service (NWS) in Sacramento. After four years as a weather officer in the USAF he transferred to the NWS office in Redding. He was the meteorologist in charge of the Redding office from 1976 until it closed in 1996. From 1996 until his retirement in 2005, he was the meteorologist in charge of the USFS Predictive Service Unit. Chris and his wife Jane have been married over 40 years and he works as a window covering installer in her business, Westwood Window Coverings.
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1 Response

  1. James Montgomery James Montgomery says:

    Very interesting analysis. I may have even learned something. We shall see. Weather maps and satellite photos may have revolutionized weather forecasting, but my old stand-bys, arthritis and Tarot cards, still have their place.