It falls under the catagory of "You might be a Redneck", saw horses or garbage cans, sheet of plywood or 2x4s on top to make a shelter. Drape a 10x12' blue trap over that. Tarp held in place with bricks. Yes, it screams Larry the CableGuy. But, you could assemble that in a few minutes if those parts were in your shed.
If you have natural gas forced air heating, have a furnace guy or an electrician wire in an outlet box & switch that you could plug an extension cord into to run the blower motor on your furnace. I don't know about D.C area but, here in Chicago durn blizzard power failure we always have Gas service but not Electric to run the fans & electronic ingnition on the furnace.
We have had to light(matches) the range burners on the stove and use the fireplace to heat the house.
Also look into how much run time you have per gallon of Gas. Be sure you have enough gas. I know that sounds obvious, like having a working flash light & batteries yet most people don't and are not prepared.