Friday, July 11, 2008 | 2:43 p.m.
As moisture rode southeasterly winds from Arizona into Southern Nevada and Southern California, a cap of renegade clouds delayed any thunderstorms from firing up in the Las Vegas Valley today, according to the National Weather Service.
In Today's Sun
Those clouds were "debris" tossed aside by Thursday night's thunderstorms that collapsed over Phoenix and Kingman, Ariz., the weather service said.
The Southwest monsoon has arrived in Arizona, but it takes some time for the wet winds to juice Southern Nevada's air enough to fire up the kinds of clouds that spawn thunderstorms, the weather service says.
Until the sun can pierce the clouds cloaking Southern Nevada's skies and heat the moist air near the ground, thunderstorms and attendant flooding will be isolated and may stay in the surrounding mountains or south of Las Vegas or even into Lincoln and Nye counties, the weather service says.
The official temperature stood at 97 degrees at 1 p.m., with an expected high of 103 degrees later this afternoon.
Relative humidity in the valley was 23 percent, when most summer thunderstorms here need humidity in the high 50- to 60 percent level.
Winds picked up to 13 mph with gusts to 18 mph, but if any isolated thunderstorms pop up later today, gusts could 50 mph to 70 mph from the thunderhead's energy, the weather service says.
The low temperature tonight could drop to 77 degrees, a change from the lows in the 80s Las Vegas has experienced since late June, the weather service says.
The forecast for tonight still has a 20 percent chance of thunderstorms until 11 p.m., then partly cloudy skies.
Saturday and Sunday Las Vegas has a better chance for experiencing thunderstorms with possible flash floods, the weather service says. By Saturday the monsoon will spread its saturated air into south and central Nevada, more of a threat for heavy rains with daytime heating that forms thunderheads like oven heat cooks a souffle, making it rise.
With increasing moisture and more clouds, Saturday's temperature is expected to reach only 98 degrees, with a 20 percent chance of showers and thunderstorms after 11 a.m.