‘Monsoon Pattern’ Through Saturday Morning Expected For Southern California

Something we have never seen before in our many years of forecasting the weather is a reversal flow in winter such as the one happening now. The flow is coming in from the southeast now through Saturday morning, bringing in moisture from where the Summer Monsoon usually brings it out of, Mexico. This will be an extremely tough forecast because not everyone will see the rain and thunderstorm activity that may be possible with it so read on.

An upper level ridge over the four corners of AZ/NM/UT/CO is going to reverse the flow starting today. This flow will bring in tropical type weather that one normally sees in our region through at least Saturday morning. There are many ingredients that are spaced out across the area and this means that it may not be possible to predict who gets what in terms of showers/tstorms till 6-12 hrs before they hit. So what we do here is called broad-brushing, a system that just says the entire region may have a chance at precipitation and there isn’t much we can do off that till the shorter term updates.

The most organized system would be the upper level low later Friday into Friday night across areas north of San Diego and east of the Coachella Valley and Inland Empire.  So the target here would be Ventura/Los Angeles County with the upper divergence and moisture.  This is still a bit far away but trends are coming together that this may accompany a small scale shower/thunderstorm event somewhere in the forecast area.

This is not a named storm system.  Elsewhere, if you do not get the shower/thunderstorm activity, expect it to be somewhat tropical in look out there with the virga (rain evaporating before it hits the ground) and pretty sunset/sunrise effects so snap the photos.