Tropical surge soon could end dry spell

Houston has gone five weeks without widespread, heavy rain, but that dry pattern could come to an emphatic end later this week.

That’s because a surge of tropical moisture in the southern Gulf of Mexico should gradually move north this week, possibly bringing multiple inches of rainfall.

Before that happens, however, Houston will enjoy one more fall-like morning Monday, with lows generally in the upper 50s across the metro area. Highs on Monday will climb to about 80 degrees.

But by Monday night, the onshore flow will resume from the Gulf of Mexico, allowing humidity levels to rise. This will bring an end to pleasant evening lows in the upper 50s and low 60s.

The region may see some scattered showers on Tuesday and Wednesday, but not until Thursday will the tropical moisture really work its way into the region.

It’s still not clear exactly what will happen, but the heaviest rains should come on Friday and Saturday.

There’s a lot of difference in model forecasts, with everything from about 1 to 10 inches

of rain possible across the Houston region.

Rainfall amounts depend in part on the movement of a low pressure system now in the southern Gulf.

There’s a small chance this low becomes a tropical depression or storm, but the effects will be the same regardless. It will be a rainmaker.

If the tropical system tracks northwest into south Texas, Houston will see less rain. But if it follows a more northward track along the Texas coast, heavier rain is more likely across the region.

In terms of flooding, given its dry spell, Houston’s soils can soak up quite a bit of rain before the region progresses beyond street flooding.

Nevertheless, tropical systems always have the potential to drop a lot of rain in a short time.

Along the coast there also will be considerable southeasterly winds and swells, with gusts as high as 50 mph right on the water by Friday or Saturday.