Weekend Storm Nudges Our Way

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This is one of those days that I was actually debating taking a day off from the blog. I’ve blogged I think every day since late October, when we converted to the much more enjoyable format that we’re using right now. It made blogging so much easier for me and allowed me to integrate things that were nearly impossible to do with the other formats we’ve used over the years.

So I got on a blog roll that hasn’t stopped. I have blogged whether I worked or not. All told that some 4+ months straight of blogging and with the weather so nice today it was going to be tough to talk about something new for you. To be honest I didn’t really have any solid ideas for a blog today. I also won’t blog just to blog. If I have something to say, I’ll go for it. If I don’t really have anything pertinent to say then I won’t. The strange thing is, is that sometimes while I may not have an idea for a blog, if I see something graphically that inspires me, then I get to thinking and hence today’s weather blog.

That’s a lot of typing for what I’m going to show you now. Oftentimes I’ll show you an image or two from a computer model. Today I re-discovered a web page that now will allow me to bring the entire model to you right here. It may take a bit of time to load on the computer but it will be pretty cool to watch the evolution of a particular storm system, like the one we’re tracking for this coming weekend. The storm in question is still well to the SW of the region. As a matter of fact it’s located down towards Mexico.

Here is a look at how the NAM model deals with it. You’re looking at the 500 mb or roughly 18K feet level of the atmosphere. It’s about halfway up into the troposphere which is just one part of the 5 parts of the atmosphere which eventually extends up to about 6200 miles above the earth. This particular level of the atmosphere is helpful for meteorologists because it helps us track some of the stronger waves (upper level storms) that move across the country, creating rising air motions below them.

I’m looking especially at the wave that is moving across northern Mexico and into Texas and eventually the deep south. Notice how that wave eventually moves along the I-20 corridor into the SE part of the country.

Here is the way the precipitation looks according to the model. The moving shades of blue/green/yellow are the precip amounts over the course of 3 hours. The totals, as depicted by the legend in the upper right corner are in mm, not inches which can be a bit confusing in the non-metric world. 1 mm=.039″ 10mm=.39″ 100mm=3.93″

The solid black lines are isobars, or lines of equal pressure. Notice how, in the Midwest, there is a closed 1024 mb line. That represents High Pressure. So on a weather map there would be a big blue H in the Midwest. Also look at the skinny pink lines. Those are what are called thickness lines. They enable us to figure out the warmth of the air through the atmosphere. They’re confusing, but typically during the winter we refer to the 540 (skinny red line) line as the approximate rain/snow line for precipitation. Follow the precip and the red line (rain/snow) through the storms evolution towards the Mid-Atlantic states. Notice what happens in the Virgina’s and parts of the OH Valley. That would be a snowstorm in the making. Here is what the model is generating for snowfall out that way.

If you click on that graphic, you’ll notice that the model is generating 10-18″ of snowfall out there! I would expect Winter storm Watches to go up for a good part of that region later today or early tomorrow AM. There may be a nice snowstorm from W KY towards N TN and into the Delmarva area over the weekend!

Back to the 500 mb maps, there are actually two streams of energy in there, of course the southern stream, which is guiding the Mexico storm, and also a northern stream, which will nudge our way over the weekend. This will 1) cool us down into the 40s and 2) there is a little disturbance in the northern stream. Can you see it? It actually closes off briefly as it moves through the region on SAT. This should help to enhance some clouds in the region on SAT., but since the southern storm will have all the moisture with it, it’ll be tough for the northern stream wave to generate much more than cloud cover. IF the two streams were to meet up, we’d have a nice storm to talk about locally around here, but since they won’t “phase” together, the weekend, while cooler, will be OK.


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