Category Archives: clouds

Explosive Growth of the Lake Fire

Development of Lake Fire pyrocumulus cloud over 10 minutes
Growth of the Lake Fire in just 10 minutes.

Lake Fire pyrocumulus cloud at about 4:21 p.m.
Lake Fire pyrocumulus cloud at about 4:51 p.m.

The photographs above show the rapid development of the pyrocumulus clouds associated with the Lake Fire, near Lake Hughes. The timestamps are approximate.

According to the Lake Fire incident page, the fire was first reported on August 12th at 3:40 p.m.

The photographs were taken during a run at Sage Ranch Park. This is the location of the Sage Peak1 and Sage Peak2 ALERTWildfire cams.

Related post: Did Lightning Start the 2002 Curve Fire?

Chivo Canyon Peaks and Clouds

Chivo Canyon peaks and clouds
Climbing out of Chivo Canyon on the way to Las Llajas Canyon

From an out and back run between Tapo Canyon and Las Llajas Canyon.

Like the Las Llajas Canyon Trail, this segment of the Chivo Canyon Trail is part of the Rocky Peak 50K course.

Los Angeles’ On and Off Rain Season is On Again

Clouds over a ridge west of Las Virgenes Canyon

Following a December with twice normal rainfall, Downtown Los Angeles (USC) experienced the fourth driest January-February on record. Now it seems the spigot has been turned back on, and March rainfall for L.A. might very well be above normal.

As of 3:00 p.m. today, March 13, Downtown Los Angeles (USC) has recorded 2.05 inches of rain this March, boosting the rain year total (since July 1) to 9.40 inches. This is about 75% of normal for the date.

More rain is forecast over the next week or so, but the major weather models differ on the projected amounts. To make up for the January-February rainfall deficit and finish the rain year close to 100% of normal, Los Angeles needs another 5.5 inches of rain by June 30.

Not impossible, given some of the forecasts, but that would be a lot of rain for this time of year. Well see!

Update July 6, 2020. Remarkably, Downtown Los Angeles (USC) ended the rain year, July 1 to June 30, within 0.07 inch of normal rainfall. It was a tumultuous rain season that saw copious rainfall in December, and then almost none in January and February — usually the wettest months of the year. Just when we started to think “drought,” the wet weather returned. Combined, Match and April precipitation was 221% of normal. That and a little rain in May brought the Los Angeles rain year total up to 14.86 inches, just short of the normal of 14.93 inches.

Update April 12, 2020. Over six consecutive days, from April 5 to April 10, Downtown Los Angeles (USC) recorded 2.96 inches of rain. This is about 325% of the normal amount for the whole month. The precipitation totals of 14.66 inches for the rain year and 14.63 inches for the water year are now above normal for the date and within about one-third of an inch of the normal annual rainfall for Downtown Los Angeles.

Update April 10, 2020. April rainfall picked up right where March left off.  As of April 9, Downtown Los Angeles (USC) has recorded 2.80 inches of rain this month. This is more than three times the normal amount of rain for the entire month of April. This brings the rain year and water year totals to 14.50 and 14.47 inches, respectively. For the first time since February 1 the rainfall totals for Los Angeles are above normal for the date. Los Angeles is now within a few tenths of an inch of normal rainfall for the year, and it is still raining today.

Update March 24, 2020. On March 22, Downtown Los Angeles (USC) set a new rainfall record for the date of 1.51 inches. As of March 24, Downtown Los Angeles has recorded 4.35 inches of rain this month. This is 179% of the normal amount of rain in March. The current rain year/water year total of 11.70/11.67 inches is about 88%/90% of normal for the date. The magic number for 100% of normal rainfall is 14.93 inches — either by June 30 (Rain Year) or September 30 (Water Year).

Update March 17, 2020. As of March 16, Downtown Los Angeles (USC) has recorded 2.80 inches of rain this month. This already exceeds the normal amount of rainfall for the entire month of March, which is 2.43 inches. The current rain year/water year total of 10.15/10.12 inches is about 79%/81% of normal for the date.

Chilly Rocky Peak

Rocky Peak following a cold Christmas storm in 2019.
Rocky Peak

Rocky Peak Road is one of my go-to wet weather running spots. The sandy soil — thanks to the Chatsworth Formation sandstone — doesn’t cake on your shoes when it’s wet. It isn’t entirely mud-free, but as long as you don’t mind a few steep hills, it’s a good choice when the weather turns wet.

According to preliminary rainfall totals tabulated by the NWS, Rocky Peak recorded 1.22 inches of rain during the Christmas storm. The snow level had been forecast to drop to 2000′-2500′ in some areas, so as the storm was breaking up I headed over to Rocky Peak to get in a run, and see what I could see.

I’d dressed for a cool and breezy run, and was comfortable as I worked up the first steep hill. But I hadn’t run half a mile when I stopped and put on some gloves and a pair of stretch shorts. That helped, but the higher I went the colder it got. Up top, a little past Rocky Peak, my thermometer registered a chilly 38 degrees and the wind was gusting 10-15 mph. According to the NWS Wind Chill chart, that put the effective temperature at around 30 degrees.

And that’s what it felt like. Part of the problem was that I was running into the wind, which increased the chill. I had a wind shell in my pack, but once I’d reached my turnaround point and had the wind at my back, it wasn’t needed.

San Gabriel Mountains following a cold Christmas 2019 storm.
Mt. Lukens, Mt. Disappointment, San Gabriel Peak and Mt. Lowe.

There was no snow on Rocky Peak Road or Oat Mountain, but from time to time the setting sun broke through the clouds and highlighted the snow on the nearby mountains. It was a far different scene than on the usual Rocky Peak run.

December has been wet in the Los Angeles area. As of December 27, Downtown Los Angeles (USC) has recorded 4.84 inches of rain this December, which is nearly three inches above normal. Rain year and water year precipitation totals are also well above normal, and at the moment, ahead of last year. We’ll see what the new year brings!

Update January 24, 2020. Well, the new year hasn’t brought us much in the way of precipitation. January in Downtown Los Angeles has been about as dry as December was wet. So far, Downtown Los Angeles has recorded only 0.32 inch of rain this January, well below the climate normal for the date. If there is no additional rain this month, Los Angeles will end the month with about normal rainfall to date for the Rain Year (Jul 1 – Jun 30) and Water Year (Oct 1 – Sep 30). Then we’ll have to see if there is a pattern change in February, or if it is also drier than normal, as most guidance suggests.

Related post: Snow on Oat Mountain (2008)