(CNN) — Heavy rain poured into Las Vegas casinos and flooded streets Thursday night as the wettest monsoon season in a decade helps alleviate the West’s severe drought — but also causes significant damage.

Rainwater poured in through a ceiling at Planet Hollywood casino, as seen in video posted by CNN affiliate KTNV, which reported 114 power outages in Clark County affecting some 12,000 people.

Rain is possible again Friday, with a slightly higher chance again through the weekend, forecasters said.

“We’re starting to sound like a broken record here, but thunderstorms are possible yet again (Friday) as well as flash flooding,” the National Weather Service said.

A flash flood watch has been posted through midnight for much of southern Nevada, northwest Arizona and far eastern California.

“Another day of slow moving thunderstorms capable of very heavy downpours and flash flooding,” the weather service said. “Little change over the weekend with rich monsoonal moisture remaining entrenched across the Mojave Desert.

“While daily storm coverage remains uncertain, flash flood risk will persist given continued slow storm motion and efficient rainfall rates.”

The robust monsoon rains in recent weeks have reduced drought levels in the Southwest — as well as the Intermountain West — to those not seen in many months. Extreme drought and extreme flooding will become more frequent and more intense as the planet warms, scientists have warned.

“Most locales in Arizona, New Mexico, the California deserts, southern Nevada, and a few other scattered areas have measured at least 200 percent of normal (rainfall) over the past 2 months,” the US Drought Monitor reported Thursday.

In Nevada, the “exceptional drought” area dropped to 4% from nearly 30% over the prior week — its lowest point in nearly two years, the report said. Conditions worsened in California’s Central Valley but improved some in the eastern deserts after the notable rains brought flooding last week to Death Valley.

In Las Vegas, Thursday’s rainfall of 0.58 inches brought the total for this year’s monsoon season to 1.28 inches, the wettest since 2012, which had 3.63 inches. Monsoon season runs from June 15 to September 30. The all-time wettest monsoon season was in 1984, with 4.16 inches.

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