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Rounds of soaking rain and a flood threat return this weekend into early next week

A man walks along the river at East Potomac Park after heavy rain on July 24, 2018, in Washington. (Salwan Georges/The Washington Post)

Since mid-July, like clockwork, every time we enjoy one or two dry days, several straight days of rainy weather closely follow. Our next stretch of wet weather starts Saturday and may persist through at least Monday.

The rain will not fall constantly, but rounds of showers and storms are likely and will be most numerous in the afternoon and evening. We’ve seen this pattern before.

Like the previous bouts of predicted rain, you don’t need to cancel all of your plans around them, but remain flexible and keep an eye on radar. Sometimes dry periods may endure beyond your expectations. Other times, it might seem as if the rain will never end.

The National Weather Service is predicting about 1.5 to two inches of rain through the middle of next week, mostly falling through Monday. However, amounts are likely to vary. Some areas could end up with double that prediction and others only half that much.

The heaviest rain should focus in narrow corridors that storms pass over repeatedly, which cannot be predicted until they start to develop.

Because we’ve seen so much rain in the past three weeks, the ground is close to saturated, and streams and creeks are nearly full. In other words, it won’t take that much heavy rain to cause flooding, especially in poor-drainage areas. Remember never to cross a flooded road and, during and just after heavy rain events, avoid routes near waterways.

The pattern responsible for the upcoming soggy weather is not unlike earlier ones. High pressure offshore will pump in tropical moisture from the Atlantic and Gulf of Mexico. At the same time, we’ll have an upper-level disturbance and front set up to our west. Our region will be caught up in a convergence zone between the two weather systems that this tropical moisture will funnel through.

Weather models suggest the upper-level disturbance should start to drift to our northeast by Tuesday, lowering the chance of rain into the middle of next week.