It's been a very unusual and wild weather day in the Las Vegas Valley today. The combination of plentiful monsoon moisture and an upper-level disturbance moving through south-central California has brought a deluge of rain, causing flash flooding.
Here are a few of the interesting statistics.
The normal high temperature is 101 today with a normal low of 79. The highest temperature today was 83, but that was before dawn. For much of the daylight hours, temperatures have been in the low 70s, 6 to 8 degrees below the normal low.
As of 2 p.m. PT, McCarran Airport has had 1.60 inches of rain, Henderson has had 2.14 inches, and Boulder City came in with 1.26 inches. It was still raining as I write this. To put this into perspective for you, the normal YEARLY rainfall is 4.20 inches. Before today, McCarran had 0.63 of an inch this month; so in the month of August, there has been more than half of the normal yearly rainfall.
Drier air will move into the Las Vegas Valley tomorrow as the richest monsoon moisture gets pushed to the east.
These is the possibility that another surge of tropical moisture could move into Arizona and Southern California by the middle of next week.
I still believe the greatest amount of rain, at least partially relating to Norbert, occurs from southeast California to Arizona
The effects on Southern California are very much in question.
With low wind shear and warm water in its path for a while longer, it is likely that Norbert intensifies into at least a Category 2 storm.
For much of the last week the monsoon moisture flow into the Southwest has been completely shut down by dry westerly winds. This is about to change.
A big pattern change is underway, one that will completely shut down any chance of showers and thunderstorms for an extended time period.