How much rain does it take to set a record this time of year in Southern California? In some areas, anything more than a trace amount will do.
It’s not that we are getting an extreme amount of rain, but rather the records that stand are so low.
Several records are expected to be broken Thursday, when between .25 and .75 inches are expected along the coast and in the valleys. An inch is expected in the mountains.
"That will give us a pretty decent amount of rain for this time of year," said NBC4 forecaster Shanna Mendiola.
The record for May 16 in downtown Los Angeles was set in 1996 -- a meager .04 inches. At LAX, the record of .05 also was set in 1996. Long Beach and Lancaster only reported a trace in 2011, enough for records.
The monthly average for May is a quarter-inch.
The wettest day recorded in May was May 8, 1977, when we got about 2 inches. What about the second half of May? The wettest late May day was back in 1990 on the 28th when we got over an inch of rain.
It's not the amount of rain, but the timing that caused problems in the form of widespread rainfall early Thursday during the morning drive. One of the toughest morning commutes was on the westbound 91 Freeway in the Corona area, where a big rig fire forced lane closures until about 6 a.m.
In Atwater Village, a fire department swift water rescue team used a raft to help two people off an island in the rain-swollen Los Angeles River channel. They did not appear to be seriously injured as they walked from the raft on the concrete bank of the river.
Rescues from the Los Angeles River are common because homeless people often stake out places to live on the riverbed, which often has little water flow until storms arrive.
Wet conditions will continue through Thursday morning, and there's a slight chance of thunderstorms and brief downpours.
Rain will fall for four to eight hours, averaging up to .20 inches per hour. That could mean street flooding and ponding water.
The average rainfall for the whole month of May is .26" and based on Thursday's rain forecast we are looking at receiving up to three times the monthly average rainfall amount in one day.
Rain will taper off Thursday after and evening before sunny conditions on Friday.
The snow level in the San Gabriel Mountains will drop to 6,000 feet. Winter driving conditions.
Rain also is in the forecast for Sunday and Tuesday.
The storm moved down from Northern California Wednesday, dumping fresh powder on the Sierra Nevada Mountains. The Mammoth Mountain resort reports a foot of new snow on its summit Thursday morning.
Some locations on the Central Coast received more than 1.5 inches of rain as the storm moved south.