Indian Ocean Signal is for Real

[Feb]

well then we can just pick different periods to verify our forecasts

That would be kind of hard considering you never issue one.

[NaoPos]

Got to like your chances on the East coast for a stormy/ chilly-qpf filled December(at least halfway) if this verifies..:

[Stebo]

That would be kind of hard considering you never issue one.

[HM]

I was able to edit and get the content from the original thread:

There has been a lot of controversy on the forum this past summer about the Indian Ocean's influence on La Niña circulation. All points from both sides of the spectrum have sound logic and this thread is by no means me suggesting that any party is correct here. I want to show the EPO relationship to forcing and how coherent this signal has been so far this autumn.

The controversy is over the actual SST relationship and that battle can go on forever because there are always going to be examples of both sides to the argument. However, the one thing that may be tough to dispute is the following logic:

1. When enhanced forcing is located over the Indian Ocean, most specifically 60-100E, the EPO tends to be positive.

2. When enhanced forcing is located at 60-100E, positive mountain torques are initiated at this stage, which begins the change in dAAM/dT, or second derivative.

3. The change in dAAM/dT in a positive direction, generally around the times of mountain torques, suggests a general +EPO tendency while the opposite is true. This is because as +AAM tendency migrates poleward from the Subtropics, this enhances the +u flow across the N-PAC, strengthening the polar vortex. During times of a -AAM tendency migration from the Tropics/Subtropics into the N Pacific, this enhances the -u flow and potentially signaling a -EPO.

Check out the next two graphics and tell me how awesome this has been. Every time there are enhanced -OLR anomalies in the 60-100E belt, the EPO goes positive and the +OLR periods, while generally weaker, signal a negative tendency on the EPO.

In September, there was a more defined propagation of the -dAAM/dT migration while the +OLR anomaly was quite substantial, so this allowed for a bigger EPO response than the early August -EPO episode.

The big question then becomes: what happens as we go forward? Already, we are seeing SST changes across the Indian Ocean, as expected with a maturing La Niña. The SST relationship to forcing is part of the equation, for sure, but may not help much this winter, especially on smaller time scales than seasonal. So, yeah, I didn't really address the core debate about the Indian Ocean, but certainly addressed the physical relationships to look for, potentially, this winter that may signal a -EPO/cold signal.

[VAwxman]

Here's the first half of Nov... Map courtesy of the fine folks at MDA.

[VAwxman]

Initially I it looks more like that I think...but it appears to try and expand W and retrograde some through the period which shoves a larger split off chunk of the PV SE into SE Canada, particularly near or after Thanksgiving. Obviously being 10+ days out, a lot can change with that prog.

Yeah essentially the ridge poking up into AK forces a chunk of the PV south, and it has nowhere to go except underneath the NAO block, which in turn gets pulled westward over the chunk of the PV, and we can get a colder period in the east. I've seen it happen like this (or similar) quite a few times. It's one reason we see many occasions where a solid -EPO can help promote the development of a solid -NAO.

[Gibbsfreeenergy]

That would be kind of hard considering you never issue one.

I am just evaluate forecasts, no forecasting needed!

[Gibbsfreeenergy]

Man what an epic torch is setup circa mid December..epic

[tacoman25]

Here's the first half of Nov... Map courtesy of the fine folks at MDA.

Tale of the first 10 days.

The majority of the month (Nov 10-30) will probably be remembered for cold/storminess across most of the northern tier. Much colder stretch likely than any recent Nina November.

Don't underestimate the power of the -EPO ridge.

[tacoman25]

Man what an epic torch is setup circa mid December..epic

And this is why you are labeled a torch fiend. We have a very impressive cold pattern setting up for much of the northern tier with exceptional blocking signals, and you are looking a month down the road for the next torch.

[Gibbsfreeenergy]

And this is why you are labeled a torch fiend. We have a very impressive cold pattern setting up for much of the northern tier with exceptional blocking signals, and you are looking a month down the road for the next torch.

you are such a sucker took the bait like I cant believe...only took you like 2 min to reply!

[VAwxman]

Tale of the first 10 days.

Not completely.

[VAwxman]

Don't underestimate the power of the -EPO ridge.

[tacoman25]

you are such a sucker took the bait like I cant believe...only took you like 2 min to reply!

Clever troll!

[JoMo]

So what's up with the Nina lately? It's been kind of 'meh'.

Or see here:

http://www.americanwx.com/bb/index.php?/topic/607-has-the-nina-peaked/

[okie333]

Yeah essentially the ridge poking up into AK forces a chunk of the PV south, and it has nowhere to go except underneath the NAO block, which in turn gets pulled westward over the chunk of the PV, and we can get a colder period in the east. I've seen it happen like this (or similar) quite a few times. It's one reason we see many occasions where a solid -EPO can help promote the development of a solid -NAO.

And the -AO should act to enhance that pattern.

[uncle W]

Here's the first half of Nov... Map courtesy of the fine folks at MDA.

[nzucker]

1954 has been almost an exact match so far but the west is certainly going to cool down a lot with the huge arctic outbreak in the coming week. The -20C 850s arriving in MT and ND won't allow those warm anomalies to stick around until the end as they did in November '54.

[keggwx]

And this is why you are labeled a torch fiend. We have a very impressive cold pattern setting up for much of the northern tier with exceptional blocking signals, and you are looking a month down the road for the next torch.

You read what you want to read....see the Power of the EPO ridge thread. Come on.

[tacoman25]

You read what you want to read....see the Power of the EPO ridge thread. Come on.

And was Gibbs posting about a big -EPO ridge and coming cold a month ago?

[Feb]

And was Gibbs posting about a big -EPO ridge and coming cold a month ago?

He was to busy looking for the heat wave hitting in mid December.

[keggwx]

He was to busy looking for the heat wave hitting in mid December.

mid December? But, but.....JB telling me Thanksgiving to Christmas will see massive cold throughout....

[Typhoon Tip]

mid December? But, but.....JB telling me Thanksgiving to Christmas will see massive cold throughout....

Why? ...seriously just asking what the forecast philosophy is for that. It may be NINO climatology - I believe that -ENSO years tend to favor early winters that end abruptly.

I think it is so odd that last year was a very Nina like winter despite NOT actually being in a Nina in the preceding months.

[New England Storm]

Why? ...seriously just asking what the forecast philosophy is for that. It may be NINO climatology - I believe that -ENSO years tend to favor early winters that end abruptly.

I think it is so odd that last year was a very Nina like winter despite NOT actually being in a Nina in the preceding months.

Last year was very odd.

[usedtobe]

Why? ...seriously just asking what the forecast philosophy is for that. It may be NINO climatology - I believe that -ENSO years tend to favor early winters that end abruptly.

I think it is so odd that last year was a very Nina like winter despite NOT actually being in a Nina in the preceding months.

Do you mean nino? Last year was very nino like, cold and wet across the south with big storms. The huge negative AO gave a different look to the midwest and plains in terms of temps but there was no hint of warmth across the south and with a strong negative NAO, that even explains the warmth across new england. At least that's my take on last year. Almost all the analogs from last year's CPC D+8 and D+11 products during the winter were el nina years.

[Typhoon Tip]

Do you mean nino? Last year was very nino like, cold and wet across the south with big storms. The huge negative AO gave a different look to the midwest and plains in terms of temps but there was no hint of warmth across the south and with a strong negative NAO, that even explains the warmth across new england. At least that's my take on last year. Almost all the analogs from last year's CPC D+8 and D+11 products during the winter were el nina years.

You're right - but once the NAO relaxed a bit, everyone stopped snowing (importantly) and the cold alleviated across the board --> warm Feb onward. That in its self didn't fit the bill of Nino. The first half of the year was Nino like, but it didn't stick for the duration.

[usedtobe]

You're right - but once the NAO relaxed a bit, everyone stopped snowing (importantly) and the cold alleviated across the board --> warm Feb onward. That in its self didn't fit the bill of Nino. The first half of the year was Nino like, but it didn't stick for the duration.

It sure was cold in Florida and the south thru mid March and then moderated. The neg nao lasted through mid March but the negative AO waned earlier than that so I guess we'll disagree. What was surprising and different was how quickly in Spring the pattern shifted to a nina like pattern. At leastthose are my memories. Glad ot see you made it over.

[Typhoon Tip]

It sure was cold in Florida and the south thru mid March and then moderated. The neg nao lasted through mid March but the negative AO waned earlier than that so I guess we'll disagree. What was surprising and different was how quickly in Spring the pattern shifted to a nina like pattern. At leastthose are my memories. Glad ot see you made it over.

Interesting. We here in New England were above normal February onward - normal for January forgiving a click perhaps... But we had Crocus shoots in early March - winter was over up this way. The idea that NE's winter was basically Dec 1 through Jan 15 was Nina like, period.

Not so for the Mid Atlantic and points south - understood. But the M/A had their best snow and cold that also ended roughly Feb 1. The deep south was cooler than normal until late, indeed.

Heh, you know, kind of a background GW interfering here I think.

[Nikolai]

Interesting. We here in New England were above normal February onward - normal for January forgiving a click perhaps... But we had Crocus shoots in early March - winter was over up this way. The idea that NE's winter was basically Dec 1 through Jan 15 was Nina like, period.

Not so for the Mid Atlantic and points south - understood. But the M/A had their best snow and cold that also ended roughly Feb 1. The deep south was cooler than normal until late, indeed.

Heh, you know, kind of a background GW interfering here I think.

Except your "idea" that winter was over for the NE 1/15 is completely wrong...

NYC/upstate NY saw major snows on 2/25-26... just because Boston had relatively little snowfall doesn't mean the rest of the Northeast had little snow after 1/15. NYC had 20" (besides another 10" with 2/11) and upstate saw 3 feet+. I don't know how you could qualify the statement that "winter was over 1/15" with that kind of snow afterwards.

The notion that "the M/A had their best snow and cold that also ended roughly Feb 1" is even more ridiculous. From 2/1-2/12, absolutely everyone in the DC-PHL corridor saw over 36" of total snow, with many passing 50" with two back-to-back 2 foot storms for some in northern Maryland. Maybe you consider Philly and DC part of the deep South, or maybe you just never heard about the storms on 2/5-6 and 2/11 AND 2/25, but your post is completely off-base and incorrect, sorry. February was NYC, PHL, BWI, and DC's snowiest on record.... I don't know how you could qualify any of your statements. Boston =/= the rest of the Northeast, and just because your backyard did poorly doesn't mean the rest of the region fared as bad--in fact, quite the opposite, and it was about time, too.

[Huffwx]

Except your "idea" that winter was over for the NE 1/15 is completely wrong...

NYC/upstate NY saw major snows on 2/25-26... just because Boston had relatively little snowfall doesn't mean the rest of the Northeast had little snow after 1/15. NYC had 20" (besides another 10" with 2/11) and upstate saw 3 feet+. I don't know how you could qualify the statement that "winter was over 1/15" with that kind of snow afterwards.

The notion that "the M/A had their best snow and cold that also ended roughly Feb 1" is even more ridiculous. From 2/1-2/12, absolutely everyone in the DC-PHL corridor saw over 36" of total snow, with many passing 50" with two back-to-back 2 foot storms for some in northern Maryland. Maybe you consider Philly and DC part of the deep South, or maybe you just never heard about the storms on 2/5-6 and 2/11 AND 2/25, but your post is completely off-base and incorrect, sorry. February was NYC, PHL, BWI, and DC's snowiest on record.... I don't know how you could qualify any of your statements. Boston =/= the rest of the Northeast, and just because your backyard did poorly doesn't mean the rest of the region fared as bad--in fact, quite the opposite, and it was about time, too.

Our last measurable snow was March 3rd down here in SW VA...there was 5 inches in parts of NC that day.