As the cold front passed through around noon and the sunshine started poking through the overcast, Adam, Chris and I went over to the window to check it out. As we looked up, we noticed something really interesting (and yes, we know we are all weather nerds). The clouds were moving in opposite directions at different levels. You could clearly see the lower-level cumulus clouds (around 2000 feet above ground level) moving from the northeast to southeast, and the mid-level altocumulus clouds (around 10,000 feet a.g.l.) moving from the southeast to northeast. Check it out for yourself.
That’s pretty neat isn’t it? Here is what was going on in the atmosphere making that happen. The two distinct cloud levels, around 950mb and 700mb, were easy to see directly after the last rain band pushed through and there was enough dry air beginning to push in behind it. There was still enough mid-level moisture for the mid-level cloud layer to exist, but not too much cool air aloft to fill in the low-layer deck as it has now in D.C. Sorry to get all technical on you. Check out this forecast sounding from the BUFKIT program we use:
Northwesterly winds have moved in at the surface directly behind the front, signaling that the cold front has pushed through the region and cooler, drier air is beginning to take over the lower levels of the atmosphere. Above the surface however, you can see the southeasterly winds and jet stream flowing to the northeast, which is what helped fuel this potent cold front through the overnight hours and brought the measurable rainfall to the region. The satellite picture around noon shows exactly what we were looking up at from our window. You can see that at the top of the post.
We know we are weather geeks for getting excited about this, but this is exactly why we do what we do. There’s nothing quite like getting excited to do your job day in and day out.