Courtesy of Weather Channel weather producer, Matthew Sitkowski, here is a photo of what Houston's East Loop at Market Street on the I-610 looks like right now. As Sitkowski says, "this image and the forecast of what is still to fall.... This is surreal." He is right: we added a photo of the same location from February 2016 to show the "before and after." Here is the result:

And another before and after photo, courtesy of Twitter user Chris Tycksen, showing downtown Houston:

And just the after:

The following time-lapse video shows the Buffalo Bayou next to Houston rising over the past day...

... and its current state:

Aerial video shows Buffalo Bayou Park in Houston as Harvey causes severe flooding in Texas https://t.co/iJHbYTFT7I

Video via @avmidas pic.twitter.com/cVV8fI63fs — NBC News (@NBCNews) August 27, 2017

The rapid raise of the Buffalo Bayou prompted the evacuation of the KHOU 11 TV studio early on Sunday morning:

Water is seeping into the studio from Buffalo Bayou. About to move broadcast to second floor. #Harvey #KHOU11 pic.twitter.com/LH80mf2uql — Janelle Bludau (@JanelleKHOU) August 27, 2017

Water coming into studio at #KHOU11... We are moving upstairs. pic.twitter.com/MMEljNatw7 — Doug Delony (@DougDelonyKHOU) August 27, 2017

Unfortunately, there is no relief in sight, as over 20 inches of rain have already fallen on the Lone Star State. With streets flooded and strewn with power lines and debris, authorities warned the storm's most destructive powers were just beginning. Rainfall that will continue for days could dump more than five feet of water and inundate many communities, including dangerously flood-prone Houston, the nation's fourth-largest city. The latest summary of rainfall in the past 24 hours can be found here. Another 20 to 30 inches of rain is expected through to Wednesday.

Meanwhile, a just issued bulletin from the NWS Houston warns that "rivers are on the rise and MAJOR to RECORD flooding is forecast."

By the time the storm ends, 40 inches of rain (a number which now appears conservative) is expected to fall and an estimated $40 billion worth of damage left behind. Putting the number in context, Hurricane Katrina cost $108 billion, mostly as a result of flooding to New Orleans.

For locals trapped in their house as floodwaters rise, the NWS Houston had some words of advice: "EMERGENCY MANAGEMENT HAS REQUESTED: IF HIGHEST FLOOR OF YOUR HOME BECOMES DANGEROUS...GET ON THE ROOF."

It's not just Houston: the following stunning video of Dickinson, TX, shows numerous boats maneuvering around stranded vehicles on flooded street.

Astounding video shows numerous boats maneuvering around stranded vehicles on flooded street in Dickinson, Texas. https://t.co/YGP3fEVW8t pic.twitter.com/LHM5SbVftF — Evan McMurry (@evanmcmurry) August 27, 2017

Finally, here is a clip from the US Coast Guard shows showing the devastation around the coastline: