National Weather Service rainfall forecast through Wednesday. (WeatherBell.com)

Enjoy Monday, and prepare your rain gear. A slow-moving coastal storm system is set to drench the region Tuesday into early Wednesday. Most areas around the D.C. region should pick up between half an inch and an inch of rain.

Rather than a sudden deluge like the one we had a week ago, this rain will come slow and steady. Our lawns, plants and flowers will love it, and need it, after a fairly dry winter and spring.

The storm is also predicted to unload upward of four inches of rain in the Southern Appalachians from western North Carolina to southwest Virginia, where flood watches are in effect. But around Washington, the rain should be gentler and generally more polite — flooding is not expected.

Timeline

Rain is likely to move into the region during the predawn hours Tuesday and fall throughout the day. The intensity should mostly be light, but moderate bursts are possible.


Simulated radar of rainfall Tuesday into Wednesday morning from NAM model.

The rain should become a bit lighter and more patchy by Tuesday night and very early Wednesday.

During the day Wednesday, lingering rain should be spotty as the center of the low-pressure system passes to our north and northeast. A slight chance of showers persists into the afternoon but shouldn’t amount to much. There’s even some chance that skies brighten a bit as the day wears on.

The overwhelming majority of the rain (at least 90 percent) from this system is likely to fall Tuesday.

Forecast amounts

The National Weather Service is predicting roughly 1.2 inches of rain around the region from this system, with slightly more likely to our southwest, especially in the mountains of Central Virginia, where 2 inches could fall.


National Weather Service rainfall forecast through Wednesday. (WeatherBell.com)

Here is what the different models are predicting around the D.C. region:

  • Canadian model: 0.6 to 0.9 inches
  • European model: 1.2 to 1.4 inches
  • GFS model: 0.4 to 0.8 inches
  • NAM model: 0.9 to 1.4 inches

We think the European model forecast is a bit overdone and favor the somewhat lower amounts predicted by the other models. We think most areas should expect between about 0.5 and 1.0 inches from this event.

Chipping away at the drought

Following a drier-than-normal fall, rainfall this calendar year is running an inch or two below normal — so the ground is a bit dry and water-depleted. A lot of the heavy rain that fell a week ago came down so hard that it ran off rather than filtered into the ground.


(U.S. Drought Monitor)

Most of the Interstate 95 corridor through and around Washington is classified as “abnormally dry” by the U.S. Drought Monitor. We even have a pocket of moderate drought through the District, southeast Montgomery and northwestern Prince George’s counties.

If this region picks up an inch of rain, it will bring totals for the year closer to normal, helping to ease these dry conditions.