Stratospheric Warming event on the way?

[usedtobe]

The euro ensembles do try and get a pretty good 10mb warming event over the N-Pole after d10. Now I don't know if this will be a classic examples of models rushing it and it gets pushed back, but just stating what it shows. As to what could be causing it....if anyone has any answers or solar flux charts...fire away. I'm also not sure if we need to be looking at where these anomalies need to be occurring. My guess is yes and per Gibbs...some of the looks of 10mb warming that occurred further south near 60N still has a warm look for another few weeks.

I don't see anything aftr day 10 but up to then, the euro shows little and nothing of note at 30 mb. Also, there are only very small ep flux changes to the temps indicated on the berlin site. I have to admit I'm not an expert but I still don't see this as a ssw event. Maybe if we get multiple warming events at 10 mb it will start to downwell but that's not guaranteed. Certainly the changes at 10mb probalby mean nothing at the trop for several weeks. At least that's my limited understanding of it all.

[am19psu]

I don't see anything aftr day 10 but up to then, the euro shows little and nothing of note at 30 mb. Also, there are only very small ep flux changes to the temps indicated on the berlin site. I have to admit I'm not an expert but I still don't see this as a ssw event. Maybe if we get multiple warming events at 10 mb it will start to downwell but that's not guaranteed. Certainly the changes at 10mb probalby mean nothing at the trop for several weeks. At least that's my limited understanding of it all.

Agree, I was saying the same thing in the OT thread.

[CoastalWx]

I don't see anything aftr day 10 but up to then, the euro shows little and nothing of note at 30 mb. Also, there are only very small ep flux changes to the temps indicated on the berlin site. I have to admit I'm not an expert but I still don't see this as a ssw event. Maybe if we get multiple warming events at 10 mb it will start to downwell but that's not guaranteed. Certainly the changes at 10mb probalby mean nothing at the trop for several weeks. At least that's my limited understanding of it all.

No you are right...it's limited until d10 and doesn't really show up until later in the 11-15 day...which makes me ask if it is being aggressive or is it for real. I'm talking 50mb temps. It's gets pretty substantial >10C anomalies at that level, but I don't know of it qualifies as major. Just sort of saying what it shows. So maybe more like a warming right now...not necessarily a SSW.

[okie333]

No you are right...it's limited until d10 and doesn't really show up until later in the 11-15 day...which makes me ask if it is being aggressive or is it for real. I'm talking 50mb temps. It's gets pretty substantial >10C anomalies at that level, but I don't know of it qualifies as major. Just sort of saying what it shows. So maybe more like a warming right now...not necessarily a SSW.

Major SSW means the mean zonal wind (NOT just the anomaly) at 10mb 60N is negative. Minor means that some point in the stratosphere warms up more than 25C compared to where it was less than 7 days before. Something very close to a minor event is happening right now at 1mb.

[Rainshadow]

You would probably like to read one of these discussions before you get too excited...

PRELIMINARY EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD

343 AM EST TUE JAN 31 2006

VALID 12Z SAT FEB 04 2006 - 12Z TUE FEB 07 2006

GLOBAL MODELS INDICATE A SCENARIO WHEREBY POSITIVE HT ANOMALIES

SPREAD FROM THE POLE INTO THE FAR NORTH ATL/ERN CANADA OVER THE

FIRST HALF OF THE MEDIUM RANGE PD...CAUSING AS A LARGE NEG HT

ANOMALY OVER THE BERING SEA TO SLOWLY SLIDE WWD. IN THE DAYS THAT

FOLLOW...BLOCKING OVER THE NORTH ATL SECTOR WILL RESULT IN A MEAN

RETGROGRESSION OF THE PATTERN WILL AT HIGH LATITUDES...WITH HTS

EVENTUALLY BUILDING OVER WRN NOAM LATE IN THE PD. THIS EVOLVING

PATTERN WILL SIGNAL A MAJOR TRANSITION TO THE WX PATTERN OVER

NORTH AMERICA...DUE IN LARGE PART TO THE MAJOR SUDDEN

STRATOSPHERIC WARMING EVENT THAT OCCURRED ON 12 JANUARY.

INCIDENTALLY...THIS SUDDEN WARMING WAS ONE OF THE STRONGEST IN THE

OPERATIONAL RECORD SINCE 1979.

Thank-you for posting this. I know it was just one occurrence and don't know where it would fit in the lag sample size, but it sounds even if something suddenly were to occur tomorrow, we'd probably be talking about late late December or January at this point for a change.

[pcbjr]

So, SSW is not "real" for now and we're basically in the same pattern until sometime into January?

Or do I mis-comprehend?

[bluewave]

Thank-you for posting this. I know it was just one occurrence and don't know where it would fit in the lag sample size, but it sounds even if something suddenly were to occur tomorrow, we'd probably be talking about late late December or January at this point for a change.

Sure. In addition to that lag, we really had to pay our dues that January with the warmth first.

January 2006

[Amped]

So, SSW is not "real" for now and we're basically in the same pattern until sometime into January?

Or do I mis-comprehend?

The pattern could change a bit. There is nothing to indicate an SSW is on the way, or that there is any above average chances for one. We don't know beyond 10 days out.

[Qaanaaq]

Excellent moderating ! Bravo.

[QVectorman]

I am not by any means an expert on ssw 's but I read a paper on it and as I recall it said there was a 2 to 4 weeks lag time from the time is the event took place until the cold reached north america. Plus, it needed time to propagate downward. I will have to look for the paper and I'll post it

[usedtobe]

I am not by any means an expert on ssw 's but I read a paper on it and as I recall it said there was a 2 to 4 weeks lag time from the time is the event took place until the cold reached north america. Plus, it needed time to propagate downward. I will have to look for the paper and I'll post it

It's probably the one from Baldwin and Dunkerton. I've posted it a couple of times recently.

[baroclinic_instability]

It's probably the one from Baldwin and Dunkerton. I've posted it a couple of times recently.

Can you post it again? Seems to be a number of publications by the two of them.

[JSTWX]

I have a feeling that this is what's getting some of the attention:

That's the most change I've seen so far this season. Of course it IS 10 days out...

[usedtobe]

Can you post it again? Seems to be a number of publications by the two of them.

I think it's this one but they also have one in nature that pretty much says the same thing and shows the same figures.

http://www.nwra.com/resumes/baldwin/pubs/SolarCycleStrat_TropDynamicalCoupling.pdf

[skierinvermont]

They might be picking up on the low level warming of the stratosphere over eastern Asia. The research I presented earlier shows this correlates with a -AO with a lag of a month or so. If this keeps up, we may be able to get some blocking by early Jan. I've found it's not just about the temperature of the entire stratosphere north of 65N, but it's also about the spatial orientation of anomalies, specifically whether it is warm/cold over eastern Asia.

Maybe wxmx can chime in as to whether this is related to the MT event he mentioned? I'm not too familiar with the effects of MT events.

[Isotherm]

I have a thread going in the NYC forum on the solar/stratospheric changes in progress:

http://www.americanw..._gopid__1189811

I posted similar maps to the one posted above -- warming is showing up, from the 100 hpa level right up through 10hpa for Asia, AK, western Canada, etc. Lowest temps appear to be shifting away from the arctic circle by 240+ hrs. Is it a major warming? Probably not, at leats doesnt look like it yet, but it's definitely a big change from the regime we've seen. I expect the arctic PV perturbation to begin over the next couple weeks, and full destruction of the +AO to be complete by early january.

[CoastalWx]

I have a feeling that this is what's getting some of the attention:

That's the most change I've seen so far this season. Of course it IS 10 days out...

Some of the models have a warming at 50mb and then weaken it a bit, so it's probably a good idea to see how it goes, but not get too excited just yet.

[JSTWX]

Some of the models have a warming at 50mb and then weaken it a bit, so it's probably a good idea to see how it goes, but not get too excited just yet.

I agree. It's probably our only shot of getting some blocking going this year...

[okie333]

Oh wow... 18Z GFS shows temps (not anomalies) at 1mb and 60N going up to 37.2C over Siberia at hour 252... 10mb level follows with readings of 3.4C in the same area (an increase of almost 50C over the temps 3 days before)... vortex at upper stratosphere is displaces and is being hammered by an ever-strengthening mega-ridge in Alaska the entire time, but doesn't split. Not sure if it's a major SSW or not as I cannot see the zonal wind, but it is at the very least an impressive minor warming event.

[Isotherm]

Oh wow... 18Z GFS shows temps (not anomalies) at 1mb and 60N going up to 37.2C over Siberia at hour 252... 10mb level follows with readings of 3.4C in the same area (an increase of almost 50C over the temps 3 days before)... vortex at upper stratosphere is displaces and is being hammered by an ever-strengthening mega-ridge in Alaska the entire time, but doesn't split. Not sure if it's a major SSW or not as I cannot see the zonal wind, but it is at the very least an impressive minor warming event.

Agree, very impressive. Might not be offically major, but it's a significant change from the current state for sure.

[okie333]

[Alpha5]

How long does it take an average SSW event to fully develop over the arctic?

[Isotherm]

How long does it take an average SSW event to fully develop over the arctic?

Generally 1-2 weeks from what I've read, then another 1-2 for the sensible weather effects, so about 2-4 weeks for the entire process. Which is why the period to watch would be after New Year's for major arctic invasion into the CONUS.

[Alpha5]

Generally 1-2 weeks from what I've read, then another 1-2 for the sensible weather effects, so about 2-4 weeks for the entire process. Which is why the period to watch would be after New Year's for major arctic invasion into the CONUS.

Yeah, I figured there would be a lag. I'm relatively new to the entire SSW thing, does the warming that begins over Asia eventually propagate through the north pole and over into Greenland, or does it stop half way?

[Ottawa Blizzard]

so it looks like JB could possibly have been right about the stratospheric warming. He tweeted today that the Chinese weather centre is calling for a cold January and February in our parts.

[ChrisM]

Can someone link a not-too-technical paper on why Stratospheric warming over asia allows for cooler temps here? Is it ridging somewhere or something?

A simple explanation would suffice! Thank you!

[dtk]

Generally 1-2 weeks from what I've read, then another 1-2 for the sensible weather effects, so about 2-4 weeks for the entire process. Which is why the period to watch would be after New Year's for major arctic invasion into the CONUS.

Right....for reference, the major SSW that took place in January 2009 saw an increase of about 50K in the 10 hPa mean polar cap (60 degrees N) temperature in about 8 days.

[donsutherland1]

Can someone link a not-too-technical paper on why Stratospheric warming over asia allows for cooler temps here? Is it ridging somewhere or something?

A simple explanation would suffice! Thank you!

A simple explanation is that the rapid warming of the stratosphere disrupts the polar vortex. As the polar vortex is disrupted, it weakens. That weakening translates into a lower, even negative, AO. The AO- teleconnects to lower heights over eastern North America. Hence, readings are typically colder. Of course, there are exceptions e.g., December 2001 saw an AO- regime, but readings remained very mild, as cold air remained locked on the other side of the globe.

[wxmx]

Can someone link a not-too-technical paper on why Stratospheric warming over asia allows for cooler temps here? Is it ridging somewhere or something?

A simple explanation would suffice! Thank you!

The kind of stratospheric warming everybody is referencing occurs in the high latitudes... there's usually a stratospheric polar vortex (low pressure) for most of the winter centered very near the north pole... if it can get displaced or splits, or at least weakened, that can propagate to the troposphere...think of a super stacked low pressure that weakens or even gets replaced by ridging...that can propagate from the top-down to the troposphere, helping build higher pressures (ridging) over the high latitudes.

[ChrisM]

A simple explanation is that the rapid warming of the stratosphere disrupts the polar vortex. As the polar vortex is disrupted, it weakens. That weakening translates into a lower, even negative, AO. The AO- teleconnects to lower heights over eastern North America. Hence, readings are typically colder. Of course, there are exceptions e.g., December 2001 saw an AO- regime, but readings remained very mild, as cold air remained locked on the other side of the globe.

The kind of stratospheric warming everybody is referencing occurs in the high latitudes... there's usually a stratospheric polar vortex (low pressure) for most of the winter centered very near the north pole... if it can get displaced or splits, or at least weakened, that can propagate to the troposphere...think of a super stacked low pressure that weakens or even gets replaced by ridging...that can propagate from the top-down to the troposphere, helping build higher pressures (ridging) over the high latitudes.

Thank you guys for the great simple explanations! I appreciate them.