Updated January 10, 2008. The ESRL-PSD Composite ENSO plots page was updated today to correct an issue that resulted in the wrong set of years being used for its Winter La Nina composites. As a result the La Nina composite precipitation map in this post has been updated.

Grasses sprouting as a result of our record setting September rainstorm have brushed our sun parched hills, fields, and woodlands with pleasing hints of green. Whether these areas will remain green depends on how much rain we receive this Fall and Winter.

According to the Climate Prediction Center's Weekly ENSO Update, issued October 1, La Niña conditions are present across the tropical Pacific and are likely to persist through early 2008. As a result, several longer range U.S. precipitation outlooks are similar to this Nov-Dec-Jan Precipitation Outlook, issued September 20 by the CPC.

The precipitation pattern projected for the western U.S. is typical of a La Niña, with an increased chance of higher than normal precipitation in the Pacific northwest and an increased chance of lower than normal precipitation in the southwest.

The September 20 CPC outlook indicates an "equal chance" of below normal, near normal, or above normal precipitation in the Los Angeles area. However, the La Niña has strengthened recently, so the next precipitation outlook may reflect a more pessimistic projection of Los Angeles area rainfall.

As mentioned above, the ESRL-PSD Composite ENSO plots page was updated today to correct an issue that resulted in the wrong set of years being used for its Winter La Nina composites. This updated precipitation map shows the mean Nov-Mar precipitation for the U.S. during 9 La Niña events from 1948 to the present. Note that the average La Niña rainfall indicated for coastal Southern California is in the 7.0-10.5 inch range, rather than the  10-15 inch range previously indicated in the ESRL-PSD graphic.

The two driest water years recorded in Los Angeles since 1877 have occurred in the last seven years. During the most recent, from Jul 2006 to June 2007, downtown Los Angeles (USC) measured only 3.21 inches of rain. In that context 10-15 inches sounds quite wet! We'll see.

The photograph of new grass sprouting amid oaks is from a run at Sage Ranch on October 1, 2007.

Los Angeles sometimes gets rain in September, but usually it is the result of tropical moisture from a dissipating hurricane, or perhaps the passage of the tail end of a weakening front. It is rare to see a low as cold, deep and energetic as the upper level low that deluged many areas of Los Angeles county Friday afternoon into Saturday.

Thunderstorms raked the San Fernando Valley Friday night, and several locations in and around the Valley recorded more than an inch of rain over the course of the storm. Los Angeles set a new rainfall record on Saturday, recording 0.40 inch of rain, and rainfall records were broken across the area.

In Southern California the first rain of the season often doesn't occur until October or November and is always savored. Especially this year, when Los Angeles has recorded only 3.21 inches of rain in the last 15 or 16 months, and a developing La Nina threatens to put the kibosh on Winter rain.

I celebrated the rain by doing an out and back run to "Fossil Point" on Rocky Peak fire road. Based on the size of the mud puddles on the dirt road, this unseasonable storm appeared to be wetter than any in last year's record dry rain season. Here's a panorama of the view northwest from the fire road to Oak Ridge, the Santa Susana Mountains and beyond.

Some related posts: San Fernando Valley from Rocky Peak, Rainy Morning on Rocky Peak Road.

With little new growth this Spring and Summer, coyote paths at Ahmanson Ranch have become so well worn that several have recently been posted with "Restoration Area - Please Keep Out" signs. Whether the canny coyotes will choose to cooperate remains to be seen.

Note: Ahmanson Ranch was acquired as open space in part to protect several sensitive species and their habitats. Some (human) use trails have evolved and "Restoration Area - Please Keep Out" signs are a reminder that the area is a preserve.

From a recent run at Upper Las Virgenes Canyon Open Space Preserve (formerly Ahmanson Ranch).

Related post: Trickster

 
Ridge between Mt. Baden-Powell and Mt. Burnham

Standing on the summit of Mt. Baden-Powell (9399'), I squinted through the haze at Mt. Baldy (10,064'). Nope, no snow. It's not often that the highest elevations of the San Gabriel Mountains are snowless on Memorial Day weekend. If nowhere else, there will usually be a patch of white on the north side of Mt. Baldy.

Five miles of (mostly) downhill to go. Running through an old growth forest of Jeffrey Pine, Sugar Pine and Incense Cedar, I relished being on a pine needle covered trail at 7000 ft. in the San Gabriel Mountains.

One of the best indicators of seasonal rainfall I've found in the oak woodland and chaparral areas of Southern California in which I run is Elegant Clarkia (Clarkia unguiculata). In a wet year it can grow more than 6 ft. tall. This year it is the shortest I've ever observed -- about 5 inches in this photo taken near Lasky Mesa.

Related posts: Elegant Clarkia, Dealing With Drought

This photograph of goldfields (Lasthenia spp.) was taken on a run on Lasky Mesa in Upper Las Virgenes Canyon Open Space Preserve almost exactly one year ago. This April I haven't seen any goldfields on Lasky Mesa. The soil is too dry for the seeds to germinate. The drought in Southern California has suppressed or delayed the growth of these, and many other species of wildflowers.

We received a little rain in the Los Angeles area earlier this week. There was just enough light rain to dampen my shirt, muddy my running shoes, and ornament this web with droplets of water. Refreshing as it was, the precipitation did little to relieve our ongoing drought.

Two runners climb up the last yards of a hill before descending into Las Virgenes Canyon in Upper Las Virgenes Canyon Open Space Preserve.

The trail is a connector that joins East Las Virgenes Canyon with upper Las Virgenes Canyon. Our 15 mile loop started at the Victory trailhead, following the El Scorpion Trail to another long-used trail that climbs up to the ridge along the northern boundary of the preserve. From here we descended to Las Virgenes Canyon and worked over to Shepherd's Flat and down Cheeseboro Canyon, eventually returning to the Victory trailhead by way of the main drag.

The area seen in the photograph is a small portion of the 24,000 acres that was burned in the Topanga Fire in late September 2005.

Although an undercoat of green is apparent, the drought in Southern California continues. According to NWS climate data, as of today, Downtown Los Angeles (USC) has recorded only 2.42 inches of rain since the water year began on July 1, 2006. This total is nearly 9 inches less than normal.

As evidenced by their survival, native plants are generally well adapted to the environment in which they live. Fire, flood, drought, heat or cold, they've seen it all – or nearly so.

Sporadic rain in the Los Angeles area has finally produced a little green in local open space areas. Here, along the margins of the "main drag" in Upper Las Virgenes Canyon Open Space Preserve (formerly Ahmanson Ranch).

As of today, (preliminary) NWS climate data indicates Downtown Los Angeles (USC) has recorded 1.92 inches of rain since July 1. This is 7.31 inches below normal. Leafing back through weather service data prior to July 1, this is the total rainfall recorded since May 22, 2006 – a period of nearly nine months.

What happened to our El Nino rains? According to NWS scientist Ed Berry, "the global circulation has been generally La-Nina like since about late November." This is despite an El Nino event that peaked in November or December, and persisted at moderate strength into January. See his blog Atmospheric Insights for the technical details.

A period of unsettled – possibly showery – weather is forecast for the Los Angeles area beginning Sunday evening and continuing pretty much through the week. At the moment* the best chance for measurable rain appears to be on Monday and Thursday. We'll see!

*Updated Saturday, February 17, at about 11:00 a.m.

Related posts: The Color of Rain, El Nino Drought, Sunset Snow Shower, Rainy Morning on Rocky Peak Road.

When I heard the news reports of snow in the Santa Monica Mountains along Kanan-Dume road near Malibu, I hoped to find a little snow or hail up at Sage Ranch Park on my afternoon run.

The isolated snow showers, hail and sleet were produced by convective cells that developed as a result of instability associated with a passing upper level low. Some of these cells also generated some lightning and thunder.

There was no snow on the ground at Sage Ranch, but the low angle rays of the setting sun did highlight a snow shower over the Rocky Peak Park area. In March of last year there was snow at Sage Ranch and Rocky Peak.

Related posts: Chumash Trail Snow, Oat Mountain Snow, San Fernando Valley from Rocky Peak.