Texas deluge the best argument for dotting California with catchments pronto

The Washington Post's Christopher Ingraham used his expertise at crunching numbers to deliver some mind-bending comparisons that put the Texas deluge in context (Visualized: How the insane amount of rain in Texas could turn Rhode Island into a lake; May 27):

It's hard to overstate the magnitude of the flooding that's hit Texas recently. The Memorial Day weekend of heavy rain has capped off a month where some areas of the state have seen more than 20 inches of rain fall. More rain is in the forecast.

It's difficult to comprehend the ridiculous amounts of water that have fallen in such a short time in a state that, until recently, had been in the grip of a historic drought. But one place to start would be to look at reservoir levels in the state. In the past 30 days, Texas reservoirs have gone from being 73 percent full to 82 percent full, according to data maintained by the Texas Water Development board. All told, about 8 million acre-feet of water have flowed into the state's reservoirs.
But how much water is that, even? [...]

After fiddling with his abacus Ingraham figured out that the 8,000,000 acre feet of rain that's fallen into Texas reservoirs during the past month is enough to:

• put the state of Rhode Island under 10 feet of water 
• meet New York City's water needs for 7 years, and is 
• nearly double the volume of water in Lake Mead

But again, the deluge wasn't enough to top the reservoirs in Texas -- although the final tally isn't in. So I wish Ingraham had totted up how full the Texas reservoirs would be if all the deluge had fallen into them and not simply turned into runoff.

The point is that a lot of the deluge didn't go into the reservoirs. Good reason for Californians to set up as many catchments as possible before the (still tentatively predicted) big rains arrive this fall. As I noted in my earlier post about this, I'd guess the best place for the catchments would be in concrete-paved areas where the rains would only dump into (and clog) storm drains.       

Speaking of predictions, the Weather Channel report that Ingraham linked to notes:

[...] Early Wednesday, another round of soaking rain descended into Houston ...
Officials in parts of Texas have warned that river flooding could last for weeks as some areas have seen more than 20 inches of rain during May. Several cities have already seen their wettest May, or even month, on record.

(MORE: Record May Rainfall)

Eidespread flash flooding also occurred in Austin this past holiday weekend. Shoal Creek was just one of many creeks and rivers that came out of its banks and flooded the area Monday afternoon.

Memorial Day weekend flooding also swamped Wimberley, Texas and several locations in Oklahoma. At least 10 deaths have been attributed to the flooding.

(MORE: Catastrophic Flooding)

Through Saturday: More Rain on the Way
A southward dip in the jet stream has been locked in place over the western states, allowing it to launch disturbances into the Plains. Those disturbances provide the necessary lift in the atmosphere to trigger thunderstorm development as they intercept a warm, moist air mass in place near the surface of the earth.

Unfortunately, that parade of upper-level disturbances will continue to pivot into the Plains the next several days, providing the instability for scattered afternoon and evening storms in the central and southern Plains.

Of most concern is the potential for slow-moving clusters of thunderstorms with locally heavy rainfall, particularly during the overnight/early morning hours, in the Plains states from parts of Kansas to Oklahoma and Texas.

Any rainfall will run off quickly because the soil is so saturated, triggering additional flash flooding. River flooding will continue on larger rivers as crests move downstream.
(INTERACTIVE MAP: Latest Flood Alerts)

It's possible that final totals for the month of May could top 30 inches in parts of Oklahoma, and it appears likely that at least one location will break the official all-time May rainfall record for the entire state, which is 23.95 inches in Miami, Oklahoma, in May 1943.

Keep in mind that slow-moving thunderstorms can produce heavier rainfall totals in localized areas in a short period of time. Also, the exact areas where the heaviest rainfall amounts occur may differ slightly from what is shown on our forecast map given that small-scale details are hard to predict several days in advance. [see website for graphics]
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