High/Low pressure question

AdamZ

AdamZ

Touchdown! Greaser!
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Feb 24, 2005
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Montgomery County PA
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Adam Zucker
I am reading aviation weather in an effort to better understand weather .Today is a nice clear windy day here in PA with some mod turb I decided to scrub my pleasure flight due to forcast high winds b/c it wouldn't be all that much fun . Then I decided to put to practice what I have been reading in Aviation Weather and was scanning the ADDS site to try and understand and predict the various types of weather around the county. There is a huge ridge of High Pressure extendinng from Central Texas to the Northwest. There also seems to be a trough of low pressure extending parallel and to the west of it, perhaps on the westernside of the sierra nevadas. What kind of weather are or could you be expecting to see between these two? due to the significant drop in pressure I would expect to see sever Wx but am not seeing it. Here is a screen shot showing the winds, isobars and pressures at the surface. Look forward to hearing your advice.


ruc00hr_sfc_wind.gif
 
Adam, I suspect that the lack of severe weather between the two systems is due to the lack of significant moisture. Those lows, are over the desert southwest. Could be that as the systems move eastward they'll pick up moisture and you'll start to see some weather east of the lows.
 
Living in the area you are talking about Adam, where that front just passed through. I can tell you what we experienced. Nothing. Still nice and sunny out. winds were blowing the last few days (10-20) might calm down to 10kts today. Really havnt seen any difference. Might be more dramatic to the coastal folks in Ca?
 
Also keep in mind those lows aren't really lows. Standard is 1013, and as Lee said, no moisture. I've crossed fronts here in the Midwest, in the summer no less and wouldn't have known it except for a required heading change and a call to FSS due to the lack of moisture.
 
So then the lack of moisture is a big key?

Ed, even though the pressures aren't that low 1013mb being standard it still seems that the drop in pressure is pretty wide 1037 to 1011. So the follow up question is: Does the disparity between "Higher and Lower Pressures" make less of a physical climatic difference the higher above standard the area is? For example a drop of 20mb where the low is near or above standard has much less of a dramatic effect than if the drop were say 15mb but the high and or low were below standard or just the low was below standard?
 
AdamZ said:
So then the lack of moisture is a big key?

Ed, even though the pressures aren't that low 1013mb being standard it still seems that the drop in pressure is pretty wide 1037 to 1011. So the follow up question is: Does the disparity between "Higher and Lower Pressures" make less of a physical climatic difference the higher above standard the area is? For example a drop of 20mb where the low is near or above standard has much less of a dramatic effect than if the drop were say 15mb but the high and or low were below standard or just the low was below standard?
Click to expand...


Things that make ya go....Hmmm....

There is some big rock, separating the differences in pressure gradients, Perhaps you might want to look at what's happening at higher altitudes ( at least wind wise). Air up there should be dry also.

AND 27 millibar = 0.391,601,893 pound/square inch ..

Not that much in the grand scheme of things, eh?
.......Three hundred ninety one millionths of a pound.....



.
 
AdamZ said:
So then the lack of moisture is a big key?

Ed, even though the pressures aren't that low 1013mb being standard it still seems that the drop in pressure is pretty wide 1037 to 1011. So the follow up question is: Does the disparity between "Higher and Lower Pressures" make less of a physical climatic difference the higher above standard the area is? For example a drop of 20mb where the low is near or above standard has much less of a dramatic effect than if the drop were say 15mb but the high and or low were below standard or just the low was below standard?
Click to expand...

Moisture, stability, and temperature differential would be the major contributing factors. High pressure usually means stable air (not factoring in geographic lifting), and all of these systems are at standard pressure or higher. Probably stable, just less stable than really stable. Alsp keep in mind that 1014 could be labaled as a high if the surrounding systems were in the 900 range.
 
I read that as Three hundred ninety-one thousandths of a pound...slight difference cosmologically speaking, but practically infinite on the sub-atomic scale.

Chache said:
Things that make ya go....Hmmm....

There is some big rock, separating the differences in pressure gradients, Perhaps you might want to look at what's happening at higher altitudes ( at least wind wise). Air up there should be dry also.

AND 27 millibar = 0.391,601,893 pound/square inch ..

Not that much in the grand scheme of things, eh?
.......Three hundred ninety one millionths of a pound.....



.
Click to expand...
 
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Steve said:
I read that as Three hundred one thousandths of a pound...slight difference cosmologically speaking, but practically infinite on the sub-atomic scale.
Click to expand...


:redface: Math, as you may have noticed, isn't one of my forte's...:no:
Always get the "point" thing with dyslexia

Anyone know where I can get one of those forehead pillows, for the :
"Duh! I could'a had a .......................................correct answer" slaps...
 
Chache said:
:redface: Math, as you may have noticed, isn't one of my forte's...:no:
Always get the "point" thing with dyslexia

Anyone know where I can get one of those forehead pillows, for the :
"Duh! I could'a had a .......................................correct answer" slaps...
Click to expand...


Wait... I looked it up.

.....
Yes,
three hundred ninety one million, six hundred one thousand, eight hundred ninety three millionths of a pound,

or as commonly "rounded up" 391 thousandths.

We're both correct.
 
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Never hurts to review ;)

http://www.factmonster.com/ipka/A0881929.html

btw, AZ, I find it more helpful to watch the wx trends than just take a snapshot of conditions. That way I have a better idea of what's coming, it rarely is going to be tomorrow exactly what it is today, or what it was an hour ago an hour from now, for that matter. And wx men are much better historians than prognisticators, anway! :)
 
Hey Adam, I noticed that the Wx map you posted changed from what it was this morning. The lows are now further east. Did you repost it, or is a live link.
 
that's just cool ... sort of like those moving photographs in the Harry Potter movies! :D
 
Temperature and moisture content, brother, temperature and moisture content.

Funny, Adam. Weather consumes most of my flying-related reading (i.e. all of my reading) time these days. I'm re-reading Buck's Weather Flying right now. Scott Dennstaedt has some great resources on his website (http://www.chesavtraining.com) if you're really interested in learning.

Good decision to scrub today. I had a very awkward ride to KPNE for a vor check. I rate my landings like the carrier guys do: good, fair, poor. Even for a crosswind landing it was a poor. Gusty and swirly winds from 280 @17g25 landing on 33. Not terrible, but the gusts were frequent. Flew home ok, with the usual wind shear plummet from the strong and gusty winds 1/2mi out on final to 24 at Wings; I was pleased to rate it a fair landing. Not a lot of fun up there for a pleasure flight. It just got worse later.
 
Wow Lee good call. The map is changing must belive. I just wanted to past a screen shot but couldn't and must have somehow copied a live link.
 
AdamZ said:
Wow Lee good call. The map is changing must belive. I just wanted to past a screen shot but couldn't and must have somehow copied a live link.
Click to expand...


It'll be interesting for people who read the beginning of this thread in the future when the map doesn't look anything like what we were discussing and they'll wonder what the hell we were talking about. :rofl:
 
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