Winter 2021-22

[PrinceFrederickWx]

23 hours ago, IronTy said:

Yeah but like last year think of all the d10 kuchera snowmaps the blocking will produce.  

If you and I can ever get below 20 degrees and/or get more than 2” of snow in an event, that would put us ahead of the last two winters.

I’m turning into Jebman- I just want deep cold at this point. If it’s not permanently killing my Camellia shrubs it’s not cold enough.

[IronTy]

47 minutes ago, PrinceFrederickWx said:

If you and I can ever get below 20 degrees and/or get more than 2” of snow in an event, that would put us ahead of the last two winters.

I’m turning into Jebman- I just want deep cold at this point. If it’s not permanently killing my Camellia shrubs it’s not cold enough.

IDK, I've got a truckload of Camellias that are 10+ft tall and they've been growing for 13yrs.  Short of Yellowstone erupting, an asteroid strike (or low solar...?) I think they're safe.  At this point just be happy with a few January nights where the ground freezes.  

[PrinceFrederickWx]

17 minutes ago, IronTy said:

IDK, I've got a truckload of Camellias that are 10+ft tall and they've been growing for 13yrs.  Short of Yellowstone erupting, an asteroid strike (or low solar...?) I think they're safe.  At this point just be happy with a few January nights where the ground freezes.  

Single digits killed one of mine in 2017-2018, but mine are much smaller. I imagine February 2015 would’ve wiped them all out. But yeah, I’ll take just an actual ground freeze at this point. Baby steps. 

[GramaxRefugee]

On 9/5/2021 at 8:41 PM, raindancewx said:

It doesn't work reliably in Baltimore/DC and south, but in La Nina years, ACE over 150 is almost a pre-requisite Summer trait for the big NE snowy winters. Pretty sure there are no La Ninas more than +20% or +30% for NYC/Philly snow totals since 1930 when ACE is not at least 150. I know you guys don't live up there, but if you hit 150 ACE in the Summer, you at least have a shot at a lot of Nor'easters with blocking.

The big ACE La Nina years since 1931-32 are these, in order of highest ACE:

1933, 2005, 1995, 2017, 1950, 1998, 2020, 1999, 2010, 1955, 1964.

If you use Baltimore, the 11-year average snowfall is (44.6+19.6+62.5+15.4+6.2+15.2+10.9+26.1+14.4+18.1+18.6)/11 --> 22.9, and essentially a coin flip for near-normal to snowy conditions using the 1991-2020 snow average.

1933-34, 2005-06, 1995-96, 1999-00, 1955-56, 1964-65 are all near average to snowy using the most recent 30 years. 2020-21 and 2010-11 would probably be snowy patterns too with less bad luck.

 

I guess we talking Atlantic ACE? This chart seems to say we're running ahead of normal for 2021, (as did 2020) That right?

 

I looked at the snow avg calculation and re-did without the highest and lowest (because I feel 1995 is just too anomalous), and still got 20.3" which didn't seem so bad. 

[WinterWxLuvr]

Can somebody explain what ACE is? Not ashamed to say I have no clue.

[GramaxRefugee]

ACE (Accumulated Cyclone Energy) is a measure of tropical cyclone energy, but I'm probably not the best guy to elaborate except to say this...

The way I look at it, things like the number of major hurricanes, or number of named storms, etc. are all subjective, since they'll name a thunderstorm these days. But the total accumulated energy is more absolute, so might be a good measure of how active the hurricane season is.

[raindancewx]

ACE is sustained winds in every named tropical storm measured every six hours, in knots. That number is squared and divided by 10,000. Each 6-hour ACE value for each storm is summed for the season.

So sustained winds of 115 mph (category three) give 100 knots. That value would 100*100 / 10,000, i.e. 1 point. If the storm was 130 kts six hours later, it would 130 * 130 / 10,000.

The ACE figures I referred to are for the Atlantic. The six hour time frame for measurement is used because it corresponds to old ship reports and things like that pre-satelite era.

[WinterWxLuvr]

Ok now that I know what ACE is, what does it have to do with winter?

[raindancewx]

ACE is pretty correlated to total snow in NYC/Philly, less so in Baltimore/DC/Boston in La Ninas. r-squared is around 0.3 in some spots in around 30 winters. Almost impossible since 1930 to get a big winter for snow without a high ACE total in a La Nina. Not a guarantee, but La Nina goes from ~0% odds for a great winter (+20-30% snow v. average) to 50% if the ACE is high enough. Look at the 11 winters for snow I listed for Baltimore above, and compare them to the lower ACE (<150) years to see it.

[WinterWxLuvr]

27 minutes ago, raindancewx said:

ACE is pretty correlated to total snow in NYC/Philly, less so in Baltimore/DC/Boston in La Ninas. r-squared is around 0.3 in some spots in around 30 winters. Almost impossible since 1930 to get a big winter for snow without a high ACE total in a La Nina. Not a guarantee, but La Nina goes from ~0% odds for a great winter (+20-30% snow v. average) to 50% if the ACE is high enough. Look at the 11 winters for snow I listed for Baltimore above, and compare them to the lower ACE (<150) years to see it.

But why? That’s the part I’m missing

[nj2va]

This makes my head hurt.  For all the x+y=z correlation stuff for snow in the DC area, we showed last year that a -NAO/-AO for sustained periods of time didn’t result in blockbuster snow totals (or even average along the coastal plain).  

Just me personally, but I’ll pass on 50 years of data/studies/correlations and just let the weather do its thing.  

[Chris78]

8 minutes ago, nj2va said:

This makes my head hurt.  For all the x+y=z correlation stuff for snow in the DC area, we showed last year that a -NAO/-AO for sustained periods of time didn’t result in blockbuster snow totals (or even average along the coastal plain).  

Just me personally, but I’ll pass on 50 years of data/studies/correlations and just let the weather do its thing.  

I'll roll the dice with a negative AO any winter. I know you know this but last years pacific was complete garbage. I think without the - ao/nao it would of been a wall to wall shut out.

[Mr. Kevin]

8 minutes ago, Chris78 said:

I'll roll the dice with a negative AO any winter. I know you know this but last years pacific was complete garbage. I think without the - ao/nao it would of been a wall to wall shut out.

A +pna also helped some because it was skewed positive last winter

[raindancewx]

The years with the highest Atlantic ACE tend to have active MJO pulses in the right phases during Summer for fun and games later on, when it gets cold. I haven't looked, but I'd expect that the increased frequency of hurricanes in some La Ninas corresponds to different strength for the subtropical high in winter, and can lead to more volatile conditions on the Atlantic side, instead of just the Pacific volatility that often shows up in La Nina winters. The strongest storms hitting the Gulf Coast (1886, 1900, 1932, 1961, 1965, 1969, 2018, 2021 as examples) also tend to occur when the Atlantic flips from AMO phase to another, and that is linked to more pronounced periods with blocking in some of the research.

[nj2va]

7 hours ago, Chris78 said:

I'll roll the dice with a negative AO any winter. I know you know this but last years pacific was complete garbage. I think without the - ao/nao it would of been a wall to wall shut out.

Yep, totally agree with you.  The favorable Atlantic kept our chances alive in spite of a hostile PAC.  Even if the pac was neutral last year, it would have been a much more memorable winter around here.  

It seems like we should root for a favorable pac and hope the Atlantic side is ok.

[mappy]

On 9/5/2021 at 8:41 PM, raindancewx said:

It doesn't work reliably in Baltimore/DC and south, but in La Nina years, ACE over 150 is almost a pre-requisite Summer trait for the big NE snowy winters. Pretty sure there are no La Ninas more than +20% or +30% for NYC/Philly snow totals since 1930 when ACE is not at least 150. I know you guys don't live up there, but if you hit 150 ACE in the Summer, you at least have a shot at a lot of Nor'easters with blocking.

The big ACE La Nina years since 1931-32 are these, in order of highest ACE:

1933, 2005, 1995, 2017, 1950, 1998, 2020, 1999, 2010, 1955, 1964.

If you use Baltimore, the 11-year average snowfall is (44.6+19.6+62.5+15.4+6.2+15.2+10.9+26.1+14.4+18.1+18.6)/11 --> 22.9, and essentially a coin flip for near-normal to snowy conditions using the 1991-2020 snow average.

1933-34, 2005-06, 1995-96, 1999-00, 1955-56, 1964-65 are all near average to snowy using the most recent 30 years. 2020-21 and 2010-11 would probably be snowy patterns too with less bad luck.

 

Are you me from my junior year of college? I did an end of the year project on ACE values from hurricane seasons and their correlation to the winters that follow 

[H2O]

This is the only ACE I know and care about

[IronTy]

14 hours ago, raindancewx said:

ACE is sustained winds in every named tropical storm measured every six hours, in knots. That number is squared and divided by 10,000. Each 6-hour ACE value for each storm is summed for the season.

So sustained winds of 115 mph (category three) give 100 knots. That value would 100*100 / 10,000, i.e. 1 point. If the storm was 130 kts six hours later, it would 130 * 130 / 10,000.

The ACE figures I referred to are for the Atlantic. The six hour time frame for measurement is used because it corresponds to old ship reports and things like that pre-satelite era.

Does ACE take into account the size of the storm too?  Seems like a 100mph hurricane with 30mi windfield would be a lot less energy than one with a 100mi windfield.  

[mappy]

1 hour ago, IronTy said:

Does ACE take into account the size of the storm too?  Seems like a 100mph hurricane with 30mi windfield would be a lot less energy than one with a 100mi windfield.  

no, storm size isn't a parameter when calculating ACE

[RDM]

16 minutes ago, mappy said:

no, storm size isn't a parameter when calculating ACE

Wasn't there some other factor floating around a couple years ago that was used to measure the relative severity of a hurricane?  Don't recall the term, but it measured the combination of several variables (wind, rain, pressure, dwell duration) and size to project a value on the relative intensity separate from the Cat 1, 2, 3 etc

[mappy]

2 minutes ago, RDM said:

Wasn't there some other factor floating around a couple years ago that was used to measure the relative severity of a hurricane?  Don't recall the term, but it measured the combination of several variables (wind, rain, pressure, dwell duration) and size to project a value on the relative intensity separate from the Cat 1, 2, 3 etc

I'm not familiar with it. 

[IronTy]

1 hour ago, mappy said:

no, storm size isn't a parameter when calculating ACE

Weird, so a moderate F3 tornado could have a computed energy higher than hurricane Katrina.  Of course the comparison is a bit disingenuous since they're not the same thing and a hurricane lasts far longer than a tornado.  Still, ACE seems rather simplistic in the computer age, at least to me.

[mappy]

4 minutes ago, IronTy said:

Weird, so a moderate F3 tornado could have a computed energy higher than hurricane Katrina.  Of course the comparison is a bit disingenuous since they're not the same thing and a hurricane lasts far longer than a tornado.  Still, ACE seems rather simplistic in the computer age, at least to me.

you're now comparing apples to oranges. ACE isn't used for tornadoes

[IronTy]

On 9/7/2021 at 9:47 AM, PrinceFrederickWx said:

Single digits killed one of mine in 2017-2018, but mine are much smaller. I imagine February 2015 would’ve wiped them all out. But yeah, I’ll take just an actual ground freeze at this point. Baby steps. 

A man can dream.

[GramaxRefugee]

If you look at a chart of Atlantic ACE Index, (below hopefully), some of the best winters had low ACE. But I think RaindanceWX is looking at La Nina years only. Which, as we all know, are usually pretty woeful winters for snow lovers, with some exceptions. Looks like the snowy winters of 2013, 2014, 2015 all had low ACE

 

[StormchaserChuck!]

Yeah, look at 2005-6

And last year

We all know 1995-6 had a lot of ACE

 

1933 had a lot of ACE

Definitely a -NAO signal. 

[WEATHER53]

Will issue outlook as usual on equinox.

Got it done and just waiting. 

[StormchaserChuck!]

I remember going through 2005-6, high CHP also goes or defaults to +EPO. same with last winter kind of 

[WinterWxLuvr]

Everybody likes a little ACE

[PrinceFrederickWx]

6 hours ago, RDM said:

Wasn't there some other factor floating around a couple years ago that was used to measure the relative severity of a hurricane?  Don't recall the term, but it measured the combination of several variables (wind, rain, pressure, dwell duration) and size to project a value on the relative intensity separate from the Cat 1, 2, 3 etc

Integrated Kinetic Energy (I think)? Which was ironic because I think Hurricane Ike was considered very high on this scale.