# Friday, October 31, 2008
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Intellicast Composite Radar Friday, October 31, 2008 - 9:30 a.m. PDT Click!
Intellicast Composite Radar
Friday, October 31, 2008 - 9:30 a.m. PDT

Downtown Los Angeles (USC) happened to be under the right cloud yesterday, and recorded 0.02 inch of rain. There's a continuing chance of showers in Southern California through the weekend. The area could use some rain. The last storm to produce more than a couple tenths of inch of rain at Downtown Los Angeles was back on February 24, 2008 -- more than eight months ago.

Last year, California's rain season might have been scripted by Dr. Jekyll and Mr. Hyde. Lowland rain totals and the Sierra snowpack were well above normal through the end of February, and then the spigot was turned off. The storm track shifted north, and California had its driest March to May on record. (The March 29, 2008 post in Ed Berry's Atmospheric Insights blog describes the events that may have led to and maintained this shift.)

Which rain season personality will emerge this Winter? Earlier this year the equatorial Pacific tried to transition to El Nino, but the atmosphere didn't cooperate. As measured by the Multivariate ENSO Index (MEI), the ENSO state has returned to the weak La Nina threshold. And as measured by the Global Wind Oscillation (GWO), an uncooperative atmosphere has continued to cycle through a La Nina base state.

This suggests a winter precipitation outlook with a La Nina flavor -- similar to last year. This precipitation map, generated by the ESRL-PSD Composite ENSO plots page, shows the mean November-March precipitation for the U.S. during 9 La Niña events from 1948 to the present. The average La Niña rainfall indicated for coastal Southern California is in the 7.0-10.5 inch range. Last season's November-March rainfall in Downtown Los Angeles was about 12 inches.

Here's the current Nov-Dec-Jan precipitation outlook issued October 16 by the Climate Prediction Center. The "EC" means an equal chance of below normal, near normal, or above normal precipitation. The IRI Multi Model Seasonal Forecast for Nov-Dec-Jan is similar. We'll see!

Update 11/4/08. Here are the NWS Public Information Statements with preliminary rainfall totals for the period from Friday evening to Sunday morning, and from overnight last night to 10:00 a.m. this morning. The current Climate Prediction Center 6-10 day and 8-14 Precipitation Outlooks project below normal rainfall for Southern California. In Atmospheric Insights, Ed Berry paints a scenario with an extended North Pacific Jet collapsing into a strong western U.S. trough in the week 2-3 timeframe. We'll see!

Update 11/1/08. Did a trail run this morning in the Pt. Mugu State Park Area. Over the course of 3+ hours watched 2-3 waves of convection march northeast from the Santa Barbara Channel across the Oxnard Plain. We were showered on a few times, but were very happy to be east of these training T-storms and heavy rain. Here is a NWS Public Information Statement with some rainfall totals as of 11:00 a.m.

More information concerning Southern California weather can be found using our WEATHER LINKS page.