Weather Experts - What’s causing this?

RyanB

RyanB

Super Administrator
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Jul 21, 2010
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Chattanooga, TN
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Ryan
I am not sure I’ve ever seen the METAR report vis at 1/8 mile.

Taking a look at the progs, there is a Low just to the south, but it’s not *that* low of pressure (1014mb). I have to say, I’ve seen foggy, but right now is just totally socked. The tops of buildings across the street are obscured.

Unusual days like this make me wonder what is actually causing conditions to be this bad, but I don’t see anything abnormal. Thoughts?

IMG_7905.jpegIMG_7906.png
 
The forecast discussion is pretty cool. The full text version is a little more in depth.
 
This is what it looks like from on top, not my photo not sure why rotated...

1733789003111.png

or this...
1733789108415.png
 
As noted, temp & dew point within 1 degree C. Plus a light wind blowing from the lake over the city means little mixing. Imagine there is a difference between the water & air temps. All that is trapped in between the hills in a low lying hallar. Topography plays a part in weather.
 
scottd said:
Yep, here's that "inversion" in the 925-850 mb layer. More of an isothermal layer rather than a true inversion.
Click to expand...
What's your source for this rendering? I like the format much better than the current version of rucsoundings.noaa.gov.
 
RyanB said:
Yeah, that discussion helped, I just didn’t realize an inversion can cause these kinds of conditions.
Click to expand...

We just had a pretty intense week-long inversion in the PacNW, and I think we had vis right about 1/8 to not much better than 1/2 for about 5 days straight at KNUW. The sun would peek out for an hour or two in the late afternoon and then everything would get socked in again. It was the first time that I remember in the 5 years I've been up here, that nearly every divert was also as bad or worse (PAE, BLI, TCM, SKA, MWH, etc.....normally if it's bad on the west side of the Cascades, the east side is nice, and vice versa). Portland/PDX was an outlier with generally decent visibility and ceilings for a lot of that time, which I imagine must have been a byproduct of the Columbia river gorge flow.
 
RyanB said:
I am not sure I’ve ever seen the METAR report vis at 1/8 mile.

Taking a look at the progs, there is a Low just to the south, but it’s not *that* low of pressure (1014mb). I have to say, I’ve seen foggy, but right now is just totally socked. The tops of buildings across the street are obscured.

Unusual days like this make me wonder what is actually causing conditions to be this bad, but I don’t see anything abnormal. Thoughts?

View attachment 136027View attachment 136026
Click to expand...

Weather Elves.

They’re responsible for that one degree spread.

Don’t they teach you new guys anything anymore?
 
RyanB said:
Yeah, that discussion helped, I just didn’t realize an inversion can cause these kinds of conditions.
Click to expand...

If the temps were colder and freezing rain was added to the scenario you posted, would that be something you are more familiar with?

The only difference is the surface temp.
 
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