10:10 p.m. Update: 10 p.m. temperatures are pretty silly. Reagan National is down to 15 with a wind chill of minus 8. Dulles is 12 with a wind chill of -7. And BWI comes in at 13 with a minus 9 wind chill. All of these are running a few degrees *below* model forecasts from earlier today.
From 5:15 p.m. … Temperatures have begun their plummet that will continue through the night. After readings started the day well above normal, in the mid-and-upper 40s, some of the coldest air in recent decades will greet us by the time we head out the door tomorrow. Add in whipping winds to go along with. Bundle up… then bundle up again!
Through Tonight: If you thought it wasn’t already cold and windy enough, this is the night for you. Winds should increase a bit heading to and through midnight as temperatures head for the teens around that time. Though wind peaks around 25 mph sustained, with gusts past 45 mph, any dwindling heading toward dawn will be quite minor. Under mostly clear skies, lows dip to near zero in the cold spots and maybe as high as around 10 downtown. Wind chill readings between -5 and -20 are possible across the area after midnight.
Tomorrow (Tuesday): The main happy news is it’s sunny. Everything else is less fortunate. Off frigid morning lows, the mercury only slowly climbs during the day toward highs ranging mostly from 11-17 across the area. Winds continue to howl around 15-20 mph from the west, with gusts near 35 mph. Wind chills rise from the -5 to -20 range early up toward the single digits below (northern ‘burbs) or above (D.C. area) zero as the day closes and winds finally ease in earnest.
A visitor from the north: Much like “derecho” took 2012 by storm, “polar vortex” is having its heyday as we speak. What was once a term relegated to the back alleys of NWS offices, private meteorological meetings, and weather geek forums has gone mainstream. The term has even trended to the top of the national list on Twitter, having seen an explosion in use there and elsewhere over recent days.
— Corey Pieper (@Geostrophic) January 6, 2014
In addition to Jason Samenow’s excellent piece explaining how the polar vortex does not disprove climate change, the National Weather Service came up with this handy infographic explaining what the polar vortex is and isn’t: