Wednesday, 11:00 a.m.
Destructive storms tore at the heart of the South on Christmas Day, with over 30 reports of tornadoes. In the end analysis, there may not be that many actual tornadoes, but that does nothing to diminish what may be the most violent outbreak of tornadoes on Christmas in recorded history. Graphically, this is what the severe weather report card looked like:
The cell that may have grabbed the biggest headlines was the one that tore through Mobile, Ala., their second tornado in the last five days! It is rare to see a town get hit twice in a year, but to have it happen near the Gulf Coast - in late December? I think the odds of winning the Powerball lottery are better than that occurrence.
The contrast in air masses from one side of the storm to the other as it developed yesterday was striking. Warm and very humid air was surging inland off the Gulf of Mexico, while much colder air will surging out of the eastern Rockies and down through Texas. And the turning of the wind from the south in the low levels to the west aloft gave these thunderstorm cells enough rotation to allow the tornadoes to form.
While somewhat similar conditions are in still in place over the eastern Carolinas this morning, the overall risk of severe weather is lower. Nevertheless, strong thunderstorms with damaging winds, hail and maybe a couple more tornadoes will sweep through the eastern Carolinas this afternoon and evening before drier, colder air drills in from the southwest to send the storms quickly offshore.
Meanwhile, on the cold side of the storm, there's snow, and plenty of it. Here's a look at the update snow cover chart this morning:
Nearly a foot of the white stuff has fallen on parts of Arkansas, and even more is expected late today into tomorrow across the northern tier of Pennsylvania and into upstate New York over to northern New England. Yes, there is some ice and rain in southwestern Pennsylvania at this hour, evidence of the primary low being located on the west side of the Appalachians at this hour:
But that low will fade this afternoon, and a new one will develop this afternoon over eastern Virginia. By early tonight, the secondary low will be deepening over Delaware Bay, and whatever warming will have taken place up into Pennsylvania will stop and begin to reverse course. It won't be fast enough to change the snow over to ice and rain across much of the southern half of the state, but it may keep the precipitation as all snow across the northern third of the state back into the Alleghenies. Furthermore, look at where the 850mb low tracks to by midnight:
If you plot out the track of the low from Nashville this morning to Morgantown, W.Va., this evening to Newark, N.J., tomorrow morning, to just south of Boston tomorrow evening, then draw a line about 50 to 75 miles north of that first plot line, you'll get a rough approximation of how far north the rain-snow line will go. Areas north of it will be mostly snow, and with the cold conveyor belt of moisture wrapping around the north side of the storm, it will be the 'sweet spot' to be in if you want a lot of snow. That helped areas of eastern Oklahoma and central and northern Arkansas, and it'll work much the same in parts of Indiana, Ohio, northern Pennsylvania, upstate New York and central and northern New England in the long run. Our latest projections:
Lest you think we get a breather after that, think again. Another storm will bring rain to southeastern Texas tomorrow night and Friday as it begins to organize, then it will streak toward the Carolina coast later Saturday. This storm won't have the same contrasts from one side of it to another, so the severe weather risk is much lower. It will also move more quickly and have less moisture to work with, so even areas that do get snow from it won't get nearly as much as what we're seeing with our current storm.
And after that, there may be a stronger storm brewing in the coffee put for New Year's Eve and New Year's Day into Wednesday. Stay tuned!
One storm is finally exiting the Northeast this afternoon, only to be replaced by another, slow-moving for the middle and latter stages of next week.
As the pattern becomes more amplified this weekend and early next week, look for it to warm up from the interior west toward the Plains, while it trends cooler east of the Mississippi.
A storm in Indiana will produce heavy rain in the mid-Atlantic into New England over the next 48 hours, but most of the rest of the nation will have little active weather into the weekend.
A powerful storm in Illinois is being blocked from a rapid advance to the East, resulting in heavy rains ahead of it, but also little cooling for the mid-Atlantic and Northeast behind it.
A strengthening storm in the eastern Plains will generate a lot of severe weather and heavy rain through Wednesday all the way to the Eastern Seaboard.
A storm developing over the southern plains late Sunday and Sunday night will help generate severe thunderstorms and flooding downpours from the Eastern Plains to the Eastern Seaboard through Wednesday.