The Rain is Coming
It's 2016, it's January (LA's wettest month, on average), and El Nino is still churning in the East Pacific. The final piece of the puzzle - the rain for LA - seems to be on our doorstep. Angelenos: Prepare for a very wet week.
STORM #1 (Sunday-Monday)
The first of 3 (maybe 4) storms this week will arrive overnight Sunday. The models have now come into agreement that a frontal system will approach the coast today, but stall somewhere off the coast near San Francisco. At this point, the front bifurcates a bit before ultimate plowing into the coast. Here's a high-resolution model forecast radar reflectivity for 1am Sunday evening showing the rain stretching from Eureka to San Francisco:
As you can see, the strong 995mb Low Pressure system generating the rain will be centered a few hundred miles East of San Francisco. A strong low this far south is what we expect with El Nino. Between 10pm Sunday and 10pm Monday we can expect anywhere from 0.5-1" of rain. Monday evening the rain will taper off from Storm #1.
But this storm is just the beginning...
STORM #2 (Tuesday)
After a brief break Monday night, a second, stronger storm will plow through the region beginning around 8am on Tuesday. A fast moving, but very potent, frontal system will take aim on Southern California, bringing a 6-10 hour period of moderate to heavy rainfall which should bring anywhere from 1-2" to the area. This storm will be a bit colder than the first storm, and with good southerly flow out ahead of the frontal passage, the San Gabriel and other south-facing mountains are really in prime location to pick up copious amounts of orographically-generated precip. Here is a look at the forecast southerly flow (wind speeds at 925mb) just ahead of frontal passage:
The foothill regions could be looking at 2-5" of rain from this storm, with snow levels gradually dipping to 5-6K feet. The rain should taper off sometime late Tuesday evening/overnight Tuesday
STORM #3(&4) (Wednesday-Friday)
The third storm in the series looks to be the coldest, and the strongest. A 990mb low well west of the CA-OR border will first push a strong frontal system into the West Coast sometime late Wednesday evening. As the low approaches the coast it will accompanied by a screaming-fast subtropical jet aimed directly at Baja, placing Los Angeles squarely in the highly dynamic front-left quadrant. This should keep showers continuing through the day on Thursday before tapering off a bit Thursday evening. The respite won't last long as the low will finally make landfall somewhere near Eureka and push one final slop of moisture into LA. The rain should finally begin to taper off by mid-day Friday. Here's a look at the jet stream aimed directly at LA for Weds-Fri:
This third (and fourth-ish) storm should bring anywhere from 1-2" of rain, and snow levels down to 3,500 feet if the models hold up.
So how much rain?
If everything plays out this week as expected, the greater LA-area could be looking at anywhere from 3-4" of rain. Here's a map showing projected rain totals for Sunday-Friday:
As usual, I'll stay on top of this all week. But, it really does appear like El Nino has finally decided to make it's move.