Between Beaumont and roughly Lufkin, an extraordinary 8 to 15 inches fell Tuesday afternoon alone, bringing storm totals in the Beaumont-Port Arthur area to around 35 inches. Torrential rains continued Tuesday evening prompting the Weather Service to issue a flash flood emergency into Tuesday night – its most severe flood alert. Rainfall rates were as high as three inches per hour and another 4 to 8 inches or more could fall overnight.
The tremendous rainfall shifted east of Houston as Harvey picked up a little speed and moved north-northeast over the Gulf of Mexico Tuesday afternoon. Its peak winds increased to 50 mph, but were not expected to strengthen further.
In southern Louisiana, rainfall intensity and amounts varied with the heaviest activity in the extreme southwest portion of the state. Along the coast, from Holly Beach to Morgan City, Louisiana, a storm surge warning was posted for water levels to rise two to four feet above normally dry land when the center of the storm approached the coast for a second landfall Tuesday night. To the east, New Orleans was under a flash flood warning Tuesday morning, but rainfall had lessened in the afternoon.
Over to Houston, in the 24 hours ending midday Tuesday, 6-12 inches of new rain had fallen, adding more water to a landmass that is fully saturated. However, rainfall intensity had substantially diminished Tuesday afternoon and mostly ended by the evening.
The total rainfall numbers from Harvey have added up to historically extreme levels. At least 5 million people in the region around Houston have seen at least 36 inches of rain (and 6 million over 30 inches). On Tuesday afternoon, a rain gauge east of the city moved past 51 inches for the storm which breaks the Texas and Lower 48 states record for the most amount of rain ever recorded from a tropical system – pending verification.
“The 3-to-4 day rainfall totals of greater than 40 inches (possible 50 inches in locations surrounding Santa Fe and Dickinson) are simply mind-blowing that has lead to the largest flood in Houston-Galveston history,” the National Weather Service office Serving Houston wrote.
Parts of Texas have seen more rain in the past four days than some major cities see in an entire year. That includes Washington D.C., which averages an annual precipitation amount of 39.74 inches.
Houston’s Hobby Airport registered its wettest, second wettest and fifth wettest day on record in the past three days.
More heavy rain is expected along the upper Texas coast Tuesday into Wednesday, with additional rainfall of 4-12 inches possible. The area east of Galveston to the border with Louisiana is the zone most likely to see these amounts.
Around Houston, there is light at the end of the tunnel. While heavy showers could still fall in the area through Tuesday night, especially in its eastern sections, drier air should continue working into the region. And rain should start to taper off from west to east Wednesday. Just one to four new inches may fall.
In south central and southeast Louisiana, including New Orleans, to coastal Mississippi and Alabama, up to a few more inches of rain was possible, but the core of Harvey’s remnants were forecast to pass to the northwest. Several inches could fall in north central Louisiana through Thursday morning.
Of course, in Houston, the flooding threat is far from over even after Harvey finally leaves the area. There is still the matter of all that water already on the ground. Much has been written in the past few days about how Houston’s rapid urban development over the last few decades has exacerbated the city’s flooding issues. It’s becoming more evident that Houston will be dealing with the after effects of Harvey for months to years, long after the storm has moved away.