atlas 14 rainfall probabilities

Wharton County Receives 13.47 Inches So Far Today

Rain is winding down for today, but areas southwest of Houston along US59 received massive amounts today. Ganado in Wharton County reported 13.47 inches at one gage and 10.87 inches at another. Radar totals indicated 10-14 inches…much of that falling in a 4-6 hour period. According to Atlas 14, that’s a 100- to 200-year rain.

Atlas 14 Rainfall Frequency Chart for this area.

A Portent of Rainfall to Come

“This shows the capability of the air mass we will be dealing with nearly all week,” said Jeff Lindner, Harris County’s meteorologist. “Expect additional “big totals” over parts of the area through the week.”

Ganado is on US 59 between Victoria and El Campo in Wharton County, southwest of Houston.

Heaviest Rains Spreading Toward Houston Later This Week

The threat of heavy to excessive rainfall will continue for the next several days and spread northeast into the Houston area. The threat of flooding and flash flooding will increase during that time, according to Lindner’s Sunday afternoon update.

Lindner predicts that we should get a break tonight, but another wave approaches on Monday late morning into the afternoon. Expect another flare up of showers and thunderstorms. “We will likely see another break on Monday night and then additional showers and storms on Tuesday,” he says.


Lindner is most concerned about Wednesday into Thursday. Another tropical air mass from the Bay of Campeche will surge into our area. Upper level winds will help lift the surface moisture into thunderstorms. Training of storms from SSW to NNE looks increasingly likely. “Potential formation of a coastal trough or weak surface low near the lower Texas coast will only help to further promote rainfall.” Given the fact that we’re still talking about forecasts three or four days out, Lindner doesn’t want to get too aggressive with rainfall total predictions just yet. But he says that models show an overall pattern favoring heavy rainfall and flash flooding.

Rainfall Amounts

Additional rainfall amounts on top of what has already fallen will average 4-8 inches over the region with isolated totals of 10-15 inches certainly possible. The expected widespread nature of the rainfall along with potential high hourly rainfall rates of 2-4 inches support rapid onset flash flooding and rises on area watersheds especially our river system as rainfall totals pile up over time. Creeks and bayous in urban areas will tend to respond to the short duration higher rainfall rates and will need to be monitored closely. 

NWS estimate of 5-day cumulative rainfall (as of Sunday afternoon, May 16) has increased since this morning.

Make sure you bookmark this page and consult it frequently throughout the week: Harris County Flood Warning System.

Posted by Bob Rehak on 5/16/2021 at 6PM based on information from NWS, HCFCD, and Space City Weather.

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