Category Archives: clouds

Winter Sky: Cirrocumulus Clouds

Cirrocumulus clouds from Upper Las Virgenes Canyon Open Space Preserve, also known as Ahmanson Ranch

Cirrocumulus clouds form at high altitude. They are primarily composed of ice crystals but also contain supercooled water droplets.

The photograph of cirrocumulus clouds was taken in Las Virgenes Canyon on a trail run from the Victory Trailhead of Upper Las Virgenes Canyon Open Space Preserve, also known as Ahmanson Ranch.

Some related posts: Pattern Change Ahead, Fallstreak Hole, Rainbow Colors in Cirrus Clouds Over Los Angeles

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?

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.