Thursday, 11:15 a.m.
Yesterday I posted about the coming warmth for next week, and that there is still a fair amount of uncertainty in just how warm it gets in any given area and for how long it stays warm. Not much has changed in that regard today, and I'll look at that in a little bit. Today, I want to look more at the concerns for a lot of wild weather across the nation, and that includes heavy rain, severe thunderstorms and, yes, even snow.
Through the weekend, the weather will be fairly peaceful. There will be a wave of low pressure that will travel by upstate New York and across northern New England Sunday, as depicted below on the 12z NAM forecast for Sunday afternoon:
With the wave there will be a little rain across the Northeast and maybe a little snow and ice for northern Maine. The main impact of this feature, though, is dragging much warmer air across the Ohio Valley into the mid-Atlantic states, boosting temperatures above normal for a change. Here's the projected temperature anomalies for Sunday:
But that's where the peacefulness of the weather ends and the volatility begins. If you look at the upper-level setup Sunday evening from the 12z NAM run, you can see a stronger system getting ready to move into the Northwest:
By the end of the day Monday, that feature should be diving into the Southwest, bringing some colder air southward with it. At the same time, it will almost assuredly spit out a disturbance or two out across the Plains toward the Ohio Valley and Great Lakes. Initially, there won't be a lot of severe weather with these features, as they'll be relatively weak, and the contrasts from one side of the disturbance won't be too large. There will, however, be some snow, particularly in parts of the northern Rockies, but perhaps even some out across North Dakota and northern Minnesota.
Even though the arctic air will largely be gone from the pattern, or at least from the U.S., it won't be totally absent. Canada will remain plenty cold, so as these disturbances move by, they'll either bring precipitation into the colder air to cause some of the snow, or they'll pull the colder air southward.
One of these disturbances will move across upstate New York and northern New England Monday and Monday night, and it looks as if it will be able to pull some chilly air southward behind it. As I pointed out in Wednesday's post, the models continue to waffle back and forth with the placement of that front. Right now, it looks as if the warmth that gets into New York and New England is pushed southward, probably out of New York City. The boundary may get all the way to northern and eastern Virginia, though much of the Ohio Valley probably stays warm. Again, let's look at the Tuesday and Wednesday GFS ensemble temperature anomaly forecasts:
What's implied by the growing contrast between the Ohio and Tennessee valleys and the Plains is that there will be a sharpening front that is just ripe to be activated by a storm or disturbance. That we're likely to see with at least one and probably two healthy surface storms. Again, the models differ on how this comes out in the wash, but you often see multiple waves in a setup like this, and I suspect that will be the case again next week.
With those healthier waves, I suspect there will be two strong outbreaks of severe weather. Areas from Texas and Oklahoma eastward into the Deep South and Tennessee Valley appear to be the areas at greatest risk for hail-bearing thunderstorms with destructive winds and possibly tornadoes, but they may get up to the Ohio River, too. And I'm betting Wednesday into Thursday is the time of greatest volatility.
On the other side of this, snow could be quite impressive from parts of Colorado eastward across northern Kansas and Nebraska into parts of the Midwest and northern Great Lakes. It's hard this far out to pinpoint where the heaviest snow would be, but those areas are at least in on the discussion for a spring snowstorm.
And while all of that is unfolding, it will get warm east of the Mississippi. MUCH warmer than it has been, and warmer than normal, too. It could reach 80 up to the nation's capital by Wednesday or Thursday if there's enough sunshine and any rain holds off, quite a contrast to the chill of recent days and recent weeks! The warmth will be welcomed, but there is likely to be a price to be paid for the relatively sudden change in weather, and that price may be paid in the form of severe weather, heavy rain, and, in some areas, heavy snow.
The countdown to spring is underway, but there's going to be plenty of cold and snow in the days ahead from the Dakotas to the mid-Atlantic and New England.
The polar vortex will roll south-southeastward over the next three days, descending upon the Great Lakes and Northeast this weekend with the coldest air mass of the winter season.
A wave of low pressure will clip the mid-Atlantic coast late tomorrow and tomorrow night, possibly resulting in some snow. A stronger storm could bring snow to parts of the East next week.
A deepening storm coming out of the Rockies and head for the Great Lakes will dump heavy snow from Colorado to Wisconsin and Minnesota, while springlike warmth will fuel severe thunderstorms from the Ohio Valley to the Gulf Coast.
Despite the historical snowfall from the Blizzard of 2016, a warm surge later this weekend and early next week will wipe out most of the snow that fell during the storm.
A major nor'easter will bring heavy, wind-blown snow through the mid-Atlantic region later Friday through Saturday, sparing much of New England of its fury.