Photo courtesy WMATA.

Metrorail and Metrobus are experiencing heavy delays due to the weather, though that was kind of a no-brainer. Metrorail is currently running on 10 to 12 minute intervals on all lines, while Metrobus is only running service on snow emergency routes. We have heard of isolated cases of bus drivers braving other roads as long as they are plowed well enough, but those cases should dwindle as conditions continue to worsen.

The real tipping point will be when — and one feels confident that it will come at some point today — the snow hits the eight-inch mark, at which point Metro will have to make a call about how long they can continue to operate above ground. At that point of accumulation, snow starts to coat the electrified third rail, cutting off power to trains. Metro was running cars all night in order to keep the rails as clear of snow as possible, but there just hits a point where the mass becomes critical, and there’s little WMATA can do.

The above map shows what the Metrorail system will look like once that call is made — as you can see, large spokes of the system are cut off from the core, so if you’re planning on taking Metro out to Alexandria, Arlington, Montgomery County or Prince George’s County, or even large parts of Northeast Washington later today, plan your trip accordingly.

In addition, the Georgetown route of the D.C. Circulator has been rerouted, and will not serve Wisconsin Avenue north of M Street — all other Circulator routes are still in service, albeit moving slowly.