UPDATE (5pm): The front has stalled and a long-duration period of moderate rainfall should linger over LA throughout the evening. Accumulations may exceed earlier predictions, but it's really difficult to predict how vigorous the dynamics will be, and whether the plume of moisture continues to hold up. For now, the radar looks nice:
The first 16 days of February have been dry as a bone. And hot. As if El Nino rains weren't significantly behind schedule at the end of January - they're now abysmally behind schedule. Los Angeles is now only at 45% of "average" through February 16, with a meager 4.2" of rain since October 1. This is an enormous deficit and runs contrary to many early-season predictions of a "blockbuster" El Nino-influenced winter with rain totals that were projected to exceed 150% of normal.
Nevertheless, it's as if mother nature just feels bad for us and is throwing us a small, mangy bone today. A surprise storm has coalesced in the Eastern Pacific. Some nice jet dynamics interacting with a fairly banal atmospheric river should bring a period of moderate to heavy rain beginning in Santa Barbara around 4pm today, spreading into Ventura and Los Angeles overnight. Here's a satellite image showing the clouds and storm lurking offshore:
Here is a gif showing the movement of the atmospheric river (blues and dark greens) through the SoCal area today and tonight:
What can we expect?
I'm calling for pretty low rainfall amounts - between 0.25 and 0.5" for the LA Metro area. Expect much less rain further south (maybe less than 0.1" in OC and points south). Upslope mountain and foothill areas could see in excess of 1" but this will need to be monitored throughout the day!
Here are two maps showing divergent rainfall total estimates (one shows 0.5-1" in LA, one shows less than 0.4"):
Either way, after more than 2 weeks of dry and HOT weather during what *should* be the wettest time of year, this little tease of a storm is welcomed.
Let's keep our fingers crossed for more :/