Saturday afternoon and night likely to be focus of weekend rain, and it could be heavy

If you want to spend time outside this weekend, Saturday morning and Sunday are probably your best options. Saturday afternoon and night could well be pretty soggy.

A disturbance is expected to develop over western North Carolina on Saturday morning along a stalled cold front and its rain should expand northward into our region Saturday afternoon, from southwest to northeast.

On Saturday, rain chances increase from 30 percent in the early afternoon to 60 percent by 5 p.m. inside the Beltway (these percentages are slightly higher to the southwest and lower to the northeast).

Rain is likely Saturday evening and night, and could be heavy at times. We can’t even rule out some embedded thunder. But it should gradually wind down between late Saturday night and Sunday morning.

On Sunday, it may still be cloudy and we can’t rule out a shower or two, but it should be dry more often than not.

Rainfall amounts

There is a lot of uncertainty in how much rain will fall. Model forecasts range from just some spotty light rain (0.1 inches) to a drenching (over 1.0 inches) in the immediate D.C. area, mostly between late Saturday afternoon and Saturday night.

The European and GFS models both suggest a slug of moderate to heavy rain will lift north over the region beginning late Saturday afternoon or early evening, with the bulk of the rain occurring between roughly 4 and 11 p.m. Both of these models predict more than an inch of rain will fall over the metro region.

The NAM model, however, forecasts a bit of a D.C. split scenario, in which substantial rain falls in the mountains and along the Delmarva Coast, but that a rain hole forms in between, along and east of Interstate 95.

The National Weather Service (top image in this post) forecast takes a blend of the different models, and forecasts about 0.5 inches of rain over the region, which we think is a reasonable compromise.

While the metro region lies in a zone of rainfall uncertainty, modeling is in good agreement that heavy rain of over an inch will affect the Interstate 81 corridor west into the mountains.

The bottom line is that you should be prepared for a period of rain, possibly heavy, Saturday afternoon and night, but don’t be totally shocked if amounts are underwhelming in the metro area and to the east.