Excessive Rainfall Likely Next Week

Tomorrow, September 10th, is the statistical peak of hurricane season.

Peak based on 100 years of data.

And the National Hurricane Center (NHC) is actively monitoring four areas in the Atlantic Basin.

As of 7PM Houston time on 9/9/2021.

Currently, a 40% Chance of Tropical Cyclone Formation

That orange area is currently where Ida and Mindy both formed in the last two weeks. In the last couple days, the NHC has steadily upgraded its chances of tropical formation. As of tonight, they give it a 40% chance sometime within the next five days.

Currently, NHC describes Area #1 as a tropical wave.

The northern portion of the wave is producing disorganized showers and thunderstorms over northeastern Honduras and the western Caribbean Sea.

This system should move into the Bay of Campeche and merge with a pre-existing heavy weather in the southwestern Gulf of Mexico this weekend. Environmental conditions support gradual development. A tropical depression could form by early next week before the system moves inland over mainland Mexico. According to NHC:

  • Formation chance through 48 hours…low…20 percent.
  • Formation chance through 5 days…medium…40 percent.

Increasing Chances of Excessive Rainfall, Likely Starting Sunday

Dry air currently over the region will yield hot days and “coolish” nights into Saturday with no chance of rainfall. However, the tropical wave will change that. A pool of deep tropical moisture will increase rain chances along the TX coast from Sunday through Wednesday of next week. It could arrive as early as Saturday evening, but more likely will arrive on Sunday.

Shower and thunderstorm activity over the western Gulf will become widespread during the weekend and into early next week. Global models are largely in agreement on a surge of moisture along the TX coast from Sunday through Wednesday. Copious rainfall is likely. 

The National Weather Service extended 7-day forecast has been increasing the forecast amounts for the north Houston area throughout the day.

Between this morning and this evening, that bright orange area has crept farther inland.

Widespread 5-7 Inches, 10-12 Possible

Jeff Lindner, Harris County Meteorologist, warns that a weak tropical cyclone could form from this. “Several models have been bouncing around with this over the last several days. They show weak closed surface lows along the Mexican or Texas coastline next week,” says Lindner. “While any sort of surface low that may form next week would help to focus rainfall in that particular area, it is unclear where any low may form if at all and generally does not change the overall wet pattern that is incoming.”

The NWS Weather Prediction Center currently shows rainfall accumulations for next week could total 5-7 inches near the coast with slightly less inland. Lindner, however, predicts that isolated areas could see as much as 10-12 inches by the middle of next week. 

No predictions have been made yet regarding potential flooding issues.

Posted by Bob Rehak on 9/9/2021 based on information from NHC, NWS, and HCFCD

1472 Days since Hurricane Harvey and 721 since Imelda