Goes-West – Sector View: Pacific Southwest | Hacker News Reader

Goes-West – Sector View: Pacific Southwest

star.nesdis.noaa.gov

24 pointshelaoban10 comments

Some of the inversion layers in California lately have been truly impressive as well in the past week. Take a look at some skew-T log-p diagrams over the past week:

Norcal (Oakland): https://climate.cod.edu/products/analysis/raob/index.php?typ... Socal (Vandenburg): https://climate.cod.edu/products/analysis/raob/index.php?typ...

If you've never seen one of these before, the blue lines of temperature (isotherms) are skewed to the right, so that everything fits on the graph, and the pressure is logarithmic so it corresponds to height. The light green lines are adiabats -- air rising or falling will follow along these lines until water condenses. The big red line is temperature, and the big green one is dewpoint temperature -- where the lines touch there's a cloud.

So what we have here are large inversion layers, where temperature increases with height. Normally, the red line goes mostly straight up the graphy, as lowering pressure should lower temperature of air. And indeed, this creates a cap, where air above and below the edge of the inversion gets trapped.

These huge inversions are why the smoke is largely staying above the ground. It rises hot from the fire, but any sinking would be countered by the buoyance of the air wanting to keep it up. Mixing at the boundary layer is slow with this strong of an inversion.

But the inversion is also low, which means that the temperature differences with altitude can be extreme. I'm on the coast in Ventura, but if you went up the hills in the same city, it would be 30°F/17°C warmer at the same time. And in LA, the 100-120°F highs a couple days ago. We're having Santa Ana winds that are literally blowing over the top of calm air below, because the pressure gradient is too weak to overcome the strong inversion. This is really crazy weather.

Dramatic photos of SF, for anyone who's missing out on the bright orange sky. https://abc7news.com/weather/photos-orange-hazy-skies-seen-a...

If I'm reading that graph correctly, over Oakland there's currently an inversion boundary at ~50m, ~1500m, ~2000m and 14000m. Is a correct interpretation that the smoke is trapped between one or several of these inversion layers, preventing both sinking and upward dispersion?

Talking about the 12Z 19 Sep sounding (you might have click back to a previous one if you read this later):

The data is a little noisy because it really is just a weather balloon getting knocked around. There's a huge inversion from 300-500m. Then the temperature is roughly constant between 1500-2500m (the T line is skewed), and we finally get a big decrease in temperature below that. The 14000m one is normal, this is called the tropopause. Normally it's a bit lower than that, but heck, even the 500mb level is at 588dm heights. It's hot out there.

So really, nothing is going to sink below that 500m point. Now, lots of Mount Diablo is above 300m -- it's going to be hot and smokey up there. But if you tried to push a parcel of air down from 500m, it would be so much less dense than the cool moist air below that it would bounce back up. The whole troposphere is very stable, but extremely so at that level.

Most people who look at skew-Ts are interested in thunderstorms -- the area of the blue line to the right of the red line tells you how much energy you can release from condensation of water, with some air from the surface rising. Like, look at Brownsville, Texas: https://climate.cod.edu/products/analysis/raob/index.php?typ...

A different view of the same data, linked in another HN thread a few months ago

long url to get you in the right area: https://rammb-slider.cira.colostate.edu/?sat=goes-17&z=3&im=...

That's definitely an interesting view. I scrolled over towards the east a bit to watch the activity of Texas. I'm fascinated by the 3-dimensional detail. You can see the lower level systems pulling in the moisture from the Gulf. You can also see the clouds over central Texas getting taller which is pretty indicative of thunderstorm activity. I can verify that by looking out the window as it heavily raining right now.

Note that the inland clouds in the geocolor view are white compared the coastal smoke.

It seems to me that you should be able to see the fires directly on one of the IR bands but I haven't found it.

They're fairly visible on band 7 IR.

I think it stands out better in band 6.

https://www.star.nesdis.noaa.gov/GOES/sector_band.php?sat=G1...

Try Natural Color-Fire (CIRA)

Much of the west coast on fire or covered in smoke.

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