The Rain Train Continues

Today it rained a lot in California. Downtown Los Angeles picked up 1.61", The foothills behind Pasadena got ~3.5", and areas by the coast received between 0.75 and 1.25". The rain was quite heavy at times, with rain rates peaking above 1 inch per hour in some spots. The main rain band moved into the area around dawn and exited LA County sometime between 2 and 3pm (a few hours earlier than I had forecast). Overall, the forecast was spot on. Here's a map of preliminary rain gauge totals:

As of January 5, Los Angeles has now picked up 2.65" of rain since October 1. This is 1.88" below "average". In fact, this is about 58% of "average". We have a lot of catching up to do if this is going to be a blockbuster rainy season. We have nudged ahead of super-dry 2013-14 and are inching closer to less-super-dry 2014-15:


The good news is that more banger storms are on the way this week. Lurking just off the coast in the East Pacific is a very powerful storm with plenty of moisture, cooperative dynamics and a whole bunch of cold air aloft (always good for rain). Here is the satellite image as of 10pm Tuesday:

If that doesn't look ominous, I don't know what does. You can see the well-defined plume associated with the main low pressure about to *storm onshore* (har har har) in Northern California. You can also see behind it a healthy open cell field indicating cold air aloft and convection.

This whole system will move onshore overnight, reaching Southern California by tomorrow morning. The best estimate is that moderate rain showers should begin around 9am Wednesday morning. Like today, rain will be heavy at times and continue through dusk. However, unlike today, the rain will not end. 

A second impulse riding along the frontal boundary will sneak under the jet streak which should provide just enough energy to amplify it as it makes landfall in Southern California around midnight / 1am on Thursday. This second impulse may be just as powerful as the first, and the combination 1-2 punch should deliver somewhere between 1 and 2 inches of rain for the basin. The rain may be more convective in nature (read: thunderstorms), and so areas caught under a stronger cell may experience very high rain rates and much higher overall rain totals. 

This second impulse should clear the area by daybreak on Thursday. Scattered showers will persist throughout the day Thursday before Northwest flow puts the LA metro in a "rain shadow" and gradually winds the precipitation down. 

The chance of showers (or at least lots of clouds) should persist through Friday, thought little accumulation is expected. 

Here's a map of modeled precipitation totals for Wednesday through Friday:

A third storm is possible during the day on Saturday, but the details are still sketchy. Stay tuned.

Mika ToscaComment