Ahead of another rainstorm, offshore pressure gradients had weakened and the onshore flow was rapidly increasing, pushing marine layer clouds into the coastal canyons of the Santa Monica Mountains and spilling over the low points of the crest.
Marine layer fog flowing between Rustic Canyon and Garapito Canyon
My first stop was going to be Temescal Peak. This little peak is about 3.5 miles from the trailhead, near the junction of Temescal Ridge fire road and the Backbone Trail. It’s a nice way to start a run, and on a clear day it can have surprisingly extensive views.
The answer to that question turned out to be no. In fact I could barely see my nose from Temescal Peak. In the 12 minutes it had taken me to get to the peak from the Hub the entire area, including the summit of Temescal Peak (about 2100′), had become enveloped in fog.
The oval disturbance in the layer of altocumulus clouds in this photograph is a relatively rare phenomenon called a fallstreak hole or hole punch cloud.
These altocumulus clouds are formed from super-cooled water droplets many times smaller than a raindrop. The droplets are in a liquid state even though the temperature is well below freezing. When disturbed by an aircraft passing through the layer the droplets freeze and precipitate out of the cloud as virga. This and other processes create the hole.
The photo was taken on Saturday, January 21, 2017 at 2:23 p.m. near the Las Virgenes trailhead of Upper Las Virgenes Canyon Open Space Preserve. The hole was well south of the area.
Not since the beginning of the drought has Downtown Los Angeles experienced such a wet December. As of December 31, 2016:
• December rainfall was 2.22 inches above the monthly normal of 2.33 inches.
• The 4.55 inches of rain recorded was the wettest December since December 2010 and the most for any month since January 2010.
Since the Rain Year began July 1, 5.95 inches of rain has fallen at Downtown Los Angeles (USC). This is 1.63 inches above the normal July-December rainfall of 4.32 inches. It is the best start to the Rain Year (Jul 1-Jun 30) and Water Year (Oct 1-Sep 30) since 2010.
The photograph of Century City and Downtown was taken from Temescal Ridge while doing the Will Rogers – Temescal Canyon loop from the End of Reseda Saturday (December 24). According to NWS records Downtown Los Angeles recorded 2.32 inches of rain from December 21 to December 24..
On my run today (Tuesday), the leading edge of the cloud shield associated with a cut-off upper level low southwest of the Los Angeles began to move into the area.
Systems such as this are notoriously difficult to forecast and computer models (and forecasters) often disagree. In this case the wetter solution won the day with a half-inch of rainfall being recorded at Downtown Los Angeles (USC) Wednesday evening.
The storm increased December’s rainfall total in Los Angeles to 2.26 inches — about 0.88 inch above normal for the month.
