Flooding rains, heavy snow, and dangerous ice are roaring groundward across the middle of the country this afternoon as a juicy series of slow-moving fronts slowly makes its way towards the coast. The disruptive storm could even push Boston to 108 inches of snow, making this the snowiest season ever recorded in the city.
The sheer size of this storm is impressive. The shield of precipitation along the fronts stretches from Chihuahua, Mexico all the way through Rhode Island, a stretch of land that spans nearly 2,100 miles. As I described yesterday, the nature of the storm system is such that just about everyone along and southeast of the winter storm advisories listed above will see the whole stretch of precipitation before temperatures plunge into record territory on Friday morning.
Forecasters expect the worst of the winter weather in the areas shaded in pink on the map above, which denotes a winter storm warning. The criteria for winter storm warnings changes from region to region—an inch of snow in Dallas has more of an impact than an inch of snow in Trenton—but it gives you a good idea of where the worst snow and ice will fall.
The jet stream is just ripping over the eastern half of the United States this afternoon, with winds closing in on 200 knots (230 MPH) about 30,000 feet over the Great Lakes. This enormous jet streak is producing quite a bit of lift in the atmosphere, and when you add that to the lifting effects of the slow-moving cold fronts (and weak low pressure centers forming along the front), you wind up with just this mass of precipitation that stretches more than half the length of the country.
Many of the areas expecting rocky weather over the next 24 hours are already seeing some pretty heavy rainfall at this hour. Rain is slowly changing over the freezing rain/sleet and eventually all snow as the cold front sags towards the southeast. As temperatures fall and precipitation changes over, roads are quickly becoming slippery and impassible in some spots.
If you haven't had the pleasure of seeing the system yet, prepare yourself, because it's going to get weird as hell over the next day. Temperatures are extremely warm across the southeastern United States right now—it's in the mid-70s as far north as The Vane's nerdquarters in central North Carolina. Rain will start as the cold front begins to swing through, but the temperature drop is what'll get you—expect readings to plummet dozens of degrees within an hour of the frontal passage.
Rain will linger longer in the south than it will in the north. The surface freezing line will approach through the early morning hours on Thursday morning, and rain will give way to a major ice storm in the southern United States, with a major snowstorm further to the north. Areas stuck in the middle—especially in places like northern parts of Arkansas, Tennessee, Mississippi, and Alabama—you will see an extended period of freezing rain, followed by a blanket of snow on top of it. The added weight of ice and snow will stress trees and power lines to their breaking point, not to mention leaving roads and sidewalks deceptively slick.
As if this isn't bad enough, temperatures will plummet below zero in the Ohio Valley on Friday morning, with lows in the teens stretching far down into the Deep South. Barring some freakish atmospheric phenomenon, this should be the last super-cold blast of air for most of the eastern U.S.
The heaviest snow accumulations will fall from eastern Kentucky through the Washington/Baltimore/Philadelphia corridor, which is where the cold air will coincide with the heavy precipitation for the longest period of time. Snow totals gradually taper off to the north and south of this band, with New York City seeing up to six inches of snow if the scenario plays out as forecast.
Boston will come so very close to breaking its all-time snowfall record for the season. The most snow ever recorded in one season was 107.6 inches back during the winter of 1995-1996, and the city has seen 105.7 inches so far this year. They just need two inches (!!) to break the record, and it looks like this storm will be a photo finish. The National Weather Service only expects about one inch of snow in Boston (the official range is one to two inches), so it'll take a small shift in the cold air (or precipitation) to make it over the record line. It's going to start warming up in the Northeast after this weekend, but it won't be too warm that snowfall is out of the question. It's still possible for Boston to break the all-time snowfall record if this storm doesn't do it.
Snow isn't the entire story, unfortunately. It's hard to see snow in the southern United States, and since warm air usually wins out around these parts, folks from Texas to Tennessee are bracing for a major ice storm tonight and Thursday morning. Parts of Arkansas, Mississippi, and Alabama could see ice accretions from freezing rain exceed one-quarter of an inch, which is usually the threshold beyond which tree and power line damage starts to become a real threat.
As previously mentioned, the storm will end as snow in most of the locations expecting ice from freezing rain will see a burst of snow towards the end of the system. Any snow that accumulates on ice will add extra weight and lead to a higher potential for power outages and tree damage.
As we so rarely get to do when talking about the weather, let's look on the bright side! These areas need the precipitation. Parts of the Ohio Valley and southern U.S. have been slipping into a drought over the past couple of months.
The ground is "abnormally dry" along the eastern feet of the Appalachians, as well as parts of the Ohio and Mississippi River valleys. The northern Gulf Coast has slipped into a moderate drought, but this is the wettest region of the country, they'll bounce back with time. The worst drought is out towards the southern Plains, with Dallas now in an "exceptional drought."
This rain isn't much, but the combination of liquid rain, ice, and snow is welcome news for regions that are drier than normal. The Weather Prediction Center expects a widespread slug of one to two inches of water-equivalent precipitation over the next seven days, in addition to the couple of inches of rain that have already fallen today. In fact, almost the entire states of Kentucky and West Virginia are under areal flood warnings this afternoon as a result of the heavy rain combining with snow melt to overflow area creeks and streams.
This is but a speed bump on the road to spring. Don't let it rattle your spirit. We've made it this far, and we'll make it to the weekend. It won't be long until it's summer and we're all whining about the heat.