At least 4 dead in Houston as severe storms lash Texas, Louisiana

• A tornado warning and also a severe thunderstorm warning that included a line referencing "destructive winds" were issued as the storms moved through.
• About 800,000 customers were without power in Texas as of Friday morning.
• "This was one of the most ferocious storms I've ever seen," meteorologist Matt Lanza of Space City Weather in Houston said in an analysis.

State of play: Surveys by NWS meteorologists have concluded that winds in downtown Houston reached 100 mph, and 90-100 mph in Baytown. (For comparison, the threshold for Category 2 hurricane winds is 96 mph.)

Houston Mayor John Whitmire at a news conference late Thursday urged people to stay home if they're not essential workers as officials were still in recovery mode across the city and the wider Harris County area.

• "We had a storm with 100 mph winds, the equivalent of Hurricane Ike," he said, noting that firefighters had pulled live wires off U.S. Route 290 that were blocking thoroughfares.
• Officials said at the news conference that several of those who died were killed by fallen trees. Whitmire said that most of the traffic lights across the city were damaged and would be down for several hours.

Zoom in: The straight-line winds hit Harris County from a surge of rain-cooled air descending toward the surface and spread out at high speeds near the leading edge of the storm.

• Damage to buildings including skyscrapers was reported across the Houston metro area and elsewhere. Storm reports to the NWS from around the metro area included "power pole snapped in half," "roof blown off" and "trees snapped."
• The Houston Independent School District announced all schools would be shut Friday and the Houston Health Department said its offices would be closed until Monday due to "widespread storm damage in the area."
• Most of the Texas power outages were in Harris County where about 700,000 customers were without power Friday morning, per utility tracker poweroutage.us.

The same severe weather system that struck Houston last night hit New Orleans Friday morning with winds as high as 84 mph.

• Over 150,000 in Louisiana were without electricity early Friday, where the storm system's heaviest rain was lashing water-logged areas.

What we're watching: With power lines down, Whitmire said it could take 24 to 48 hours to restore electricity to residents — and the region faces hot conditions with highs in the mid-90s forecast through the weekend.

• Meanwhile, heavy to excessive rainfall was forecast for eastern Louisiana into central Alabama. The NWS said it could bring flash, urban and riverine flooding Friday.
• "Scattered severe thunderstorms with a few tornadoes, very large hail, and damaging winds are possible across parts of the Gulf Coast States Friday and Friday night," the NWS said in a Friday morning forecast discussion.

Zoom out: In addition to the punishing wind event Thursday night, heavy rains have lashed Gulf Coast states for weeks.

Context: The latest storms erupted around the northern edge of a powerful heat dome that has brought record heat to Central America and Florida in recent weeks.

• Human-caused climate change has caused such extreme heat events to become more common and intense.
• Studies have shown that climate change is also causing extreme precipitation events to be more intense and frequent.

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Editor's note: This article has been updated with new details throughout. Axios Houston's Jay Jordan contributed reporting.