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Misc General Banter Thread

EthanLovesWeather said:
That’s definitely true. I guess the deeper question is: does the 540 thickness line mean the same today as it did 50-75 years ago, in that more variables have to fall in place now for it to be the (relatively) true rain/snow changeover line because of how average 500 mb heights for, say 40° north, over North America during DJF have steadily risen overall since the 1960s for all of mid latitude CONUS. In other words, what used to be the upper air norm is not normal now.
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Ethan,
Along with warming avg sfc temps, things like avg 850 mb temps and avg 500 mb have also risen. Related to this, I’d think that avg thicknesses have also risen. So, I assume that it’s harder to get a sub 540 dm thickness than it was when the globe was cooler.

But, is it actually harder for it to snow given a 540 thickness? I haven’t read anything clearly saying that. So, perhaps not. It’s just that 540 thickness lines are apparently creeping a bit further north as the earth continues to warm.

Here’s a link to an article that I found interesting:

wu-next-prod.wunderground.com

The 540 Line: A Rule Of Thumb Meteorologists Use To Determine The Snow Versus Rain Line

Here's a little winter weather forecasting 101 on a general rule of thumb meteorologists use for the rain versus snow line.
wu-next-prod.wunderground.com

The model forecast map below shows the 540 line draped just south of the Great Lakes on the morning of Monday, Oct. 14. But in most of those areas outside of higher terrain, rain instead of snow was falling.

That's because despite the thickness of the atmosphere being ripe for snow well above the ground by hundreds or thousands of feet, the air located near the surface where we live was too mild, or warmer than 32 degrees, meaning the snowflakes melt into raindrops. This can often happen both early in the fall and later in spring when the source of cold air is modest, but we even see this in midwinter on occasion.

So while the 540 line is a good first stab at determining the rain versus snow line, meteorologists don't stop there. They often look at several other model forecasting charts to further hone in on where snow versus rain will occur.

Not to add confusion, but my observations for the SE have actually told me that the 546 thickness is often a better rain/snow line indicator in mid-winter than 540! Also, I prefer to use the 0C 850 mb line if precip is steady enough.
 
GaWx said:
Ethan,
Along with warming avg sfc temps, things like avg 850 mb temps and avg 500 mb have also risen. Related to this, I’d think that avg thicknesses have also risen. So, I assume that it’s harder to get a sub 540 dm thickness than it was when the globe was cooler.

But, is it actually harder for it to snow given a 540 thickness? I haven’t read anything clearly saying that. So, perhaps not. It’s just that 540 thickness lines are apparently creeping a bit further north as the earth continues to warm.

Here’s a link to an article that I found interesting:

wu-next-prod.wunderground.com

The 540 Line: A Rule Of Thumb Meteorologists Use To Determine The Snow Versus Rain Line

Here's a little winter weather forecasting 101 on a general rule of thumb meteorologists use for the rain versus snow line.
wu-next-prod.wunderground.com

The model forecast map below shows the 540 line draped just south of the Great Lakes on the morning of Monday, Oct. 14. But in most of those areas outside of higher terrain, rain instead of snow was falling.

That's because despite the thickness of the atmosphere being ripe for snow well above the ground by hundreds or thousands of feet, the air located near the surface where we live was too mild, or warmer than 32 degrees, meaning the snowflakes melt into raindrops. This can often happen both early in the fall and later in spring when the source of cold air is modest, but we even see this in midwinter on occasion.

So while the 540 line is a good first stab at determining the rain versus snow line, meteorologists don't stop there. They often look at several other model forecasting charts to further hone in on where snow versus rain will occur.

Not to add confusion, but my observations for the SE have actually told me that the 546 thickness is often a better rain/snow line indicator in mid-winter than 540! Also, I prefer to use the 0C 850 mb line if precip is steady enough.
Click to expand...
Excellent synopsis and link, thank you for that.
 
SnowNiner said:
Starting to not be a fan of the pattern coming up. It's just not cold for MBY. Cold is bottled up NW. Tilt of the western ridge, etc, it's just not flowing the cold into the SE. Patiently waiting for models to show cold.

View attachment 181717
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The models have been showing cold lol. It’s just bouncing around like it always does. We will focus in on some threats by weekends end.
 
SNOWMANN said:
I think next Thursday could turn into something. Need that baby to dig a little more. We got our cold coming in. Several systems have potential and we're in prime climo. I remember January 2017 was looking grim and then we got that storm around Martin Luther King Day. I believe good times are ahead.
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I don't remember a storm around MLK Day in 2017 but I do remember North Georgia getting a few inches of snow on Jan 6-7, 2017 !
 
SnowNiner said:
Thank you! That's great data. This literally is why "it don't snow like it used to". lol. But yeah, we're not imagining things when we say snow was better back when we generation x'ers were kids because the tropical forcing was better it seems.

I think to fix this we need to get together and dump a bunch of ice in the West Pacific Warm Pool, likely causing alot of this.
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A few years ago I suggested SouthernWx sponsor a member cruise to the W Pac warm pool, provide tons of ice, and let us all dump a bunch of ice there. Maybe we can see if @Jimmy Hypocracy will provide his fail-boat for the cruise.
 
Drizzle Snizzle said:
It's been so dry lately in most of the south, and this next rainmaker is going to be mostly dry east of the Apps. What makes you think that all of a sudden when it gets cold that the moisture is going to return ? We can't even get moisture when its warm !
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The southern jet is waking up.
 
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