Its not about car racing…. though that might be more exciting than what I am going to write about. This is a discussion about 500 millibar maps and what you can get out of them.
Here’s this morning’s 5 AM AST 500 millibar pressure map below. Knowing that sea level pressure averages 1013.6 millibars, then 500 millibars, around 18,000 feet or so, is about halfway through, in pressure anyway, ALL the air above us that we have on this planet. Thins out, of course, as you go higher; 10 millibars, for example, is around 120, 000 feet above sea level. You don’t want to be there. Thought I would check around for that height of the 10 millibar level, and here’s what I came across
At this link on the web, however, it is calculated that the 10 millibar level is reached at “5.48 miles” above sea level, and at 4 miles above the sea level, about 21,000 feet, the pressure is but “13.44 mb”! I started laughing because you’d need a space suit to be at the top of our Mt. Lemmon with a vertical pressure distribution like theirs. Yikes! No wonder our math and science scores are behind those in the developed countries!
The pressure at 4 miles above sea level (at 21,000 feet) averages about FOUR HUNDRED FIFTY millibars, not “13”, fer Pete’s Sake, and its still about 320 millibars at the top of Mt. Everest, about 5.5 miles above sea level. I guess these folks don’t do any hiking above about 1,000 feet above sea level. Might be too dangerous without an oxygen bottle in the atmosphere they’re making calculations for. (Looks like someone mixed units; English and metric in their calcs.)1
Now, where was I?
Oh, yeah, this morning’s 500 millibar map… Note where the wind maximum is around a cold trough that is about to pass over us, the one that extends across Utah to Vegas. The peak wind is just about over us, and as the day goes by, it drifts farther south. So what, you say?
Check below where the moisture is at mountain top level, or around 700 millibars, 3 km or about 10,000 feet above sea level.
Later today, that green area will be over us and there’ll be some scattered showers. Cloud bases will be high, higher than Mt. Lemmon, and so the precip is going to be pretty marginal. Will be very happy if even a few hundredths of an inch falls in Catalina this afternoon or evening. BTW, with the freezing level so low again this afternoon, soft hail (graupel, tiny snowballs) falling from these clouds is a certainty this afternoon or early this evening. (I’ve repeated some of this in the caption below…. Hmmm. Mind going.)
Here is the latest surface map of obs and infrared satellite imagery on top of the obs from the U of AZ. And, if you look out the window now, adding this at 6:45 AM, you’ll see the first clouds with this trough, likely good enough for a bit of sunrise color here in Catalina.
What’s ahead? Storms
Storm world, that’s what’s ahead because we’re in the bowl now, the trough bowl, resulting intermittent periods of storminess, broken by deceptively nice weather for several days; the latter, times of some trough fakery, one that make you think the “bowl” is gone. But then its BACK! So, don’t be afraid when the weather turns nice again after today.
Here is a sequence of maps from IPS MeteoStar ones that document what I am trying so poorly to explain, the overall spell of storms that we’re in, where one cold trough after another is drawn to Arizona like metal filings to a magnet. First the “interruptus”, now on deck, a map for about five days from now. For some reason, I put all of what it means in the caption.
In conclusion, and remembering that these exact depictions above are not going to be realized as such, they will vary in intensities and positioning; nevertheless, the prediction from this keyboard is that February 2013 will have ABOVE NORMAL precip in just about all of Arizona due to storms that occur in the last 15 days. I am really happy for you, and its always great to conclude things like this, conclusions that bring so much happiness to others.
Mr. CMP, in a twinge of conscience, realizes that the error he goes on about today is one that he himself would like have made during his struggles in math and physics in HS and college.