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Pattern Freezing Ferocious February

Clayton Reid said:
Incredible. Just two days ago, we were talking about the pattern change to cold, and now that is completely out the window it seems. Even if it's delayed, who knows if it'll be good enough for a big dog. Confidence way down at this point fellas.
Click to expand...

My confidence level is around 90%.
For one it hasn’t been delayed, it’s always been Feb 3-5 onward.

I’d admit at h5 it doesn’t look pretty, yet (it will), but a few things to keep in mind:
1. We don’t live at 500mb, thankfully
2. Models and ensembles usually have a very tough time with PV drops. In fact, many of the past PV drops kind of “snuck up” on us to the point where I remember back in 2013(?) I believe, where raleigh got down to the single digits, that PV drop showed up on a control run. Also, it’s incredibly hard for a statistical model to translate stratosphere to lower levels his dad out.

At least now we have the advantage of knowing it’s not going to sneak up on us, and we have a number of factors helping argue for cold as mentioned in this thread (MJO, -EPO off the charts, Climo favored month, Displacement/splitting of the PV in the stratosphere consistently modeled)

It’s ok not the trust Op models. They’re guidance and not gospel. A day ago there were 100 new posts just out of full fledged excitement. Now hardly any - and I can promise it’s due to watching operational runs and forgetting the “big picture”

Let’s take a look at the 24 hour GFS ensemble trend (5 day mean) for Feb 4-9:

5822aa64577729e4df1444a74ba5d4f9.jpg


To some the “cupping” ridge over the southern US is an eye sore, but really it’s par for the course when a large anomalous PV drops down to Hudson Bay. The models have to compensate and put ridging somewhere, especially when it’s this far out.

As you can see in the first image we had a positively tilted trough in the west, gross- but:

You can see the changes here just in 24 hours. We need the SER giving us issues to move to the Atlantic, to essentially bridge the two troughs, one over Hudson Bay (our PV) the other towards Scandinavia. This would give the ridging out west no choice but to move more east, and again the PV will adjust slightly more east, setting up shop for deep cold over the central and eastern US.
9cc462797c2f6d7d7e805a0a6777a957.jpg
 
Jon said:
My confidence level is around 90%.
For one it hasn’t been delayed, it’s always been Feb 3-5 onward.

I’d admit at h5 it doesn’t look pretty, yet (it will), but a few things to keep in mind:
1. We don’t live at 500mb, thankfully
2. Models and ensembles usually have a very tough time with PV drops. In fact, many of the past PV drops kind of “snuck up” on us to the point where I remember back in 2013(?) I believe, where raleigh got down to the single digits, that PV drop showed up on a control run. Also, it’s incredibly hard for a statistical model to translate stratosphere to lower levels his dad out.

At least now we have the advantage of knowing it’s not going to sneak up on us, and we have a number of factors helping argue for cold as mentioned in this thread (MJO, -EPO off the charts, Climo favored month, Displacement/splitting of the PV in the stratosphere consistently modeled)

It’s ok not the trust Op models. They’re guidance and not gospel. A day ago there were 100 new posts just out of full fledged excitement. Now hardly any - and I can promise it’s due to watching operational runs and forgetting the “big picture”

Let’s take a look at the 24 hour GFS ensemble trend (5 day mean) for Feb 4-9:

5822aa64577729e4df1444a74ba5d4f9.jpg


To some the “cupping” ridge over the southern US is an eye sore, but really it’s par for the course when a large anomalous PV drops down to Hudson Bay. The models have to compensate and put ridging somewhere, especially when it’s this far out.

As you can see in the first image we had a positively tilted trough in the west, gross- but:

You can see the changes here just in 24 hours. We need the SER giving us issues to move to the Atlantic, to essentially bridge the two troughs, one over Hudson Bay (our PV) the other towards Scandinavia. This would give the ridging out west no choice but to move more east, and again the PV will adjust slightly more east, setting up shop for deep cold over the central and eastern US.
9cc462797c2f6d7d7e805a0a6777a957.jpg
Click to expand...
Thank you I've been trying to find out about how all the warm air stays in here just because of an MJO being so off the charts even though everything else says we should be cold PNA AO all of them if I'm correct say we get cold. I wouldn't understand how the MJO could basically kick them to the curb and make us warm
 
GaWx said:
My brand new research on the 18 very strong MJO events since 1975

1. Dec-Mar MJO mag 3+: 18 events totaling 213 days (I include all surrounding days with MJO magnitude of 2.5+ as a single event)

Facts about these 18 events at ATL:

- 1 MB, 2 B, 5 N, 6 A, 4 MA:
-8, -6, -3, -1, -1, -1, +1, +1, +3, +3, +4, +6, +7, +7, +8, +9, +11, +14

- 213 days averaged 2.4 warmer than normal

- The 3 B to MB were in 2/1978, 3/1981, and 1-2/1985. We've had 15 events since and all were near N (5) or A/MA (10)

-------------------------------------------------------------------------------------------------------------------------------
2. Dec.-Mar MJO mag 3+ events that included phase 7: 9 events totaling 100 days

Facts about these 9 events at ATL:

- 1 MB, 2 N, 2 A, 4 MA: -6, -1, +1, +7, +7, +8, +9, +11, +14

- 100 days averaged 5.7 warmer than normal

--------------------------------------------------------------------------------------------------------------------------------
3. Dec-Mar MJO mag 3.5+ events: 7 events totaling 119 days

Facts about these 7 events at ATL:

- 1 B, 3 N, 2 A, 1 MA: -6, -1, -1, -1, +7, +7, +11

- 119 days averaged 2.0 warmer than normal

--------------------------------------------------------------------------------------------------------------------------------
4. Dec-Mar MJO mag 3.5+ events that included phase 7: 4 events totaling 66 days

Facts about these 4 events at ATL:

- 1 N, 2 A, 1 MA: -1, +7, +7, +11

- 66 days averaged 6.0 warmer than normal

-------------------------------------------------------------------------------------------------------------------------------
Conclusion: No matter which way I look at it, although a few have been cold in the SE US and the next one could be cold, the stats show that having a very strong MJO, itself, in Dec-Mar without considering other indices doesn't favor cold over warm in the SE. If anything, it favors warm over cold. This is consistent with my prior research as well as that from MDA.
Click to expand...

This still doesn't explain why strong MJO events are warmer than weaker ones, especially just for the SE US only, this seems fishy without a plausible physical explanation and examination of other areas of the country, or more stations, because looking at Atlanta only is also going to skew the data. I know you have previously looked at other stations but what makes this part of the country so special vs the upper midwest, Great Lakes, Rockies, etc? The sample size is also an issue when you considering strong (magnitude +3.0 or more) events, having a sample of only nine is not going to cut it. Have you tried the VPM or OMI MJO indices because many of the events, especially in the western hemisphere, which were perceived as "weak" in RMM (because it's noisy) were correspondingly much stronger in one or both of these indices. As I mentioned earlier, it's actually very possible that this is an artifact of the data in RMM or just random chance, strong MJO events only encompass a very tiny subset of days relative to those where the MJO is weak, it's very possible that only several exceptionally warm days or a few very warm periods in the midst of a strong MJO event are skewing the data heavily in favor of warmth. While your particular sample may not capture this, there's a non-stationary trend in the MJO over the last several decades, with more intense MJO events generally occurring more frequently in concurrence with the warmer background climate.

Annual MJO Amplitude time series.png
 
Clayton Reid said:
Incredible. Just two days ago, we were talking about the pattern change to cold, and now that is completely out the window it seems. Even if it's delayed, who knows if it'll be good enough for a big dog. Confidence way down at this point fellas.
Click to expand...
Good grief. Totally over the top. Great opportunities lie ahead.
 
IMG_0872.PNG

Lol as Dr Ventrice showed this morning, the Euro weeklies completely messed this up, they're about 8-10C colder over the Canadian Rockies and several degrees cooler over our neck of the woods for this week compared to last week's week 2 forecast (same time period). Fail.
 
Clayton Reid said:
Incredible. Just two days ago, we were talking about the pattern change to cold, and now that is completely out the window it seems. Even if it's delayed, who knows if it'll be good enough for a big dog. Confidence way down at this point fellas.
Click to expand...
Thank you for the report Mr Sunshine. This cool/colder period has always been modelled as after the first week or 2 of February, nothing's changed
 
Jon said:
My confidence level is around 90%.
For one it hasn’t been delayed, it’s always been Feb 3-5 onward.

I’d admit at h5 it doesn’t look pretty, yet (it will), but a few things to keep in mind:
1. We don’t live at 500mb, thankfully
2. Models and ensembles usually have a very tough time with PV drops. In fact, many of the past PV drops kind of “snuck up” on us to the point where I remember back in 2013(?) I believe, where raleigh got down to the single digits, that PV drop showed up on a control run. Also, it’s incredibly hard for a statistical model to translate stratosphere to lower levels his dad out.

At least now we have the advantage of knowing it’s not going to sneak up on us, and we have a number of factors helping argue for cold as mentioned in this thread (MJO, -EPO off the charts, Climo favored month, Displacement/splitting of the PV in the stratosphere consistently modeled)

It’s ok not the trust Op models. They’re guidance and not gospel. A day ago there were 100 new posts just out of full fledged excitement. Now hardly any - and I can promise it’s due to watching operational runs and forgetting the “big picture”

Let’s take a look at the 24 hour GFS ensemble trend (5 day mean) for Feb 4-9:

5822aa64577729e4df1444a74ba5d4f9.jpg


To some the “cupping” ridge over the southern US is an eye sore, but really it’s par for the course when a large anomalous PV drops down to Hudson Bay. The models have to compensate and put ridging somewhere, especially when it’s this far out.

As you can see in the first image we had a positively tilted trough in the west, gross- but:

You can see the changes here just in 24 hours. We need the SER giving us issues to move to the Atlantic, to essentially bridge the two troughs, one over Hudson Bay (our PV) the other towards Scandinavia. This would give the ridging out west no choice but to move more east, and again the PV will adjust slightly more east, setting up shop for deep cold over the central and eastern US.
9cc462797c2f6d7d7e805a0a6777a957.jpg
Click to expand...

You can tell in that timeframe it looks like the STJ is starting to kick in. If we can just get everything to shift east like you describe we'd really be in business. I hope it does.
 
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Reactions: Jon
Looks like a stout clipper that taps a little Atlantic moisture. Certainly not a setup as good as the last event. But, as I said earlier this month, if we can rack up a few flurries or a period of light snow during an unfavorable period, that's a win.
 
Webberweather53 said:
This still doesn't explain why strong MJO events are warmer than weaker ones, especially just for the SE US only, this seems fishy without a plausible physical explanation and examination of other areas of the country, or more stations, because looking at Atlanta only is also going to skew the data. I know you have previously looked at other stations but what makes this part of the country so special vs the upper midwest, Great Lakes, Rockies, etc? The sample size is also an issue when you considering strong (magnitude +3.0 or more) events, having a sample of only nine is not going to cut it. Have you tried the VPM or OMI MJO indices because many of the events, especially in the western hemisphere, which were perceived as "weak" in RMM (because it's noisy) were correspondingly much stronger in one or both of these indices. As I mentioned earlier, it's actually very possible that this is an artifact of the data in RMM or just random chance, strong MJO events only encompass a very tiny subset of days relative to those where the MJO is weak, it's very possible that only several exceptionally warm days or a few very warm periods in the midst of a strong MJO event are skewing the data heavily in favor of warmth. While your particular sample may not capture this, there's a non-stationary trend in the MJO over the last several decades, with more intense MJO events generally occurring more frequently in concurrence with the warmer background climate.

View attachment 3459
Click to expand...

1. The last 15 very strong MJO events (going back to 1988) have been either near normal or warmer in the SE US. If you specifically look at those that included phase 7, they have averaged even warmer. I think my dataset size is decent enough to give the general idea that a very strong phase 7 doesn't by itself favor a cold SE. Can it still end up cold this time even if it were to end up very strong? Of course it can based on other factors like +PNA and -AO and it may end up cold. But my study says a very strong phase 7 by itself doesn't specifically say it is likely going to get cold in the SE. I think JB and others are misinformed in thinking a very strong MJO by itself screams cold down here.

2. All of my research is based on RMM data due to there being 42 years of readily available data and because we're talking about a projected very strong MJO (4) on the GEFS and still strong (2.5) on the EPS on the RMM (I.e., apples to apples). I still by the way am forecasting it will come in
much closer to the EPS' 2.5 based on GEFS strong tendency to oversimplify. So, that actually may help some for the SE since it wouldn't actually be "very strong" but instead just "strong".

3. I use ATL/SE US because that's what I'm addressing since that's where we live and we want to know how the very strong MJO tends to influence our wx, not Joe Blo in Chicago or NYC. That's what makes the SE "special". And I don't see a statistical credibility issue with just examining the SE US.

4. Possible physical reason per MDA pro mets: very strong MJO favors more warmth from
the tropics lessening Arctic influence.

5. I just talked to MDA met. He agrees totally with my analysis as well as my prediction that the phase 7 peak will be much closer to the EPS' 2.5 than the GEFS' 4.0 due to bias of GEFS way overdoing past MJOs. He also said the projection by the Euro suite is for the MJO to be weak once it gets to phases 8-1-2, which would then favor colder in the SE. That I agree with. So, if the +PNA, -AO, weak MJO phases 8-1-2 were to then coexist, it would then favor a cold SE mid February. Phil has been ontonthis idea. In essence, I think the cold may end up delayed but not denied in the SE. I mainly think that folks are expecting it to occur too soon.
 
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GaWx said:
1. The last 15 very strong MJO events (going back to 1988) have been either near normal or warmer in the SE US. If you specifically look at those that included phase 7, they have averaged even warmer. I think my dataset size is decent enough to give the general idea that a very strong phase 7 doesn't by itself favor a cold SE. Can it still end up cold this time even if it were to end up very strong? Of course it can based on other factors like +PNA and -AO and it may end up cold. But my study says a very strong phase 7 by itself doesn't specifically say it is likely going to get cold in the SE. I think JB and others are misinformed in thinking a very strong MJO by itself screams cold down here.

2. All of my research is based on RMM data due to there being 42 years of readily available data and because we're talking about a projected very strong MJO (4) on the GEFS and still strong (2.5) on the EPS on the RMM (I.e., apples to apples). I still by the way am forecasting it will come in
much closer to the EPS' 2.5 based on GEFS strong tendency to oversimplify. So, that actually may help some for the SE since it wouldn't actually be "very strong" but instead just "strong".

3. I use ATL/SE US because that's what I'm addressing since that's where we live and we want to know how the very strong MJO tends to influence our wx, not Joe Blo in Chicago or NYC. That's what makes the SE "special". And I don't see a statistical credibility issue with just examining the SE US.

4. Possible physical reason per MDA pro mets: very strong MJO favors more warmth from
the tropics lessening Arctic influence.

5. I just talked to MDA met. He agrees totally with my analysis as well as my prediction that the phase 7 peak will be much closer to the EPS' 2.5 than the GEFS' 4.0 due to bias of GEFS way overdoing past MJOs. He also said the projection by the Euro suite is for the MJO to be weak once it gets to phases 8-1-2, which would then favor colder in the SE. That I agree with. So, if the +PNA, -AO, weak MJO phases 8-1-2 were to then coexist, it would then favor a cold SE mid February. Phil has been ontonthis idea. In essence, I think the cold may end up delayed but not denied in the SE. I mainly think that folks are expecting it to occur too soon.
Click to expand...
Except the delay in cold may be wasted unless you know of some decent storms in Late February and early March that aren't just marginal and are very cold or cold afterwards with it being very warm or warm in early February through mid February. Cold being delayed won't help us with a good winter storm is what I'm afraid of unless you can prove me wrong. And please don't use very rare unlikely events like the 93 superstorm
 
Clayton Reid said:
Except the delay in cold may be wasted unless you know of some decent storms in Late February and early March that aren't just marginal and are very cold or cold afterwards with it being very warm or warm in early February through mid February. Cold being delayed won't help us with a good winter storm is what I'm afraid of unless you can prove me wrong. And please don't use very rare unlikely events like the 93 superstorm
Click to expand...

I didn't say warm all of the way "through mid Feb". I'm thinking mid itself could easily be cold. Mid to late Feb: many winter storms in SE have occurred.
 
Brad Panovich just tweeted out a great animation of the polar vortex settling in and producing cold. The biggest takeaway I saw from the animation is the SER getting beaten down. I’m on my phone and can’t post it. Maybe someone else can.
 
GaWx said:
1. The last 15 very strong MJO events (going back to 1988) have been either near normal or warmer in the SE US. If you specifically look at those that included phase 7, they have averaged even warmer. I think my dataset size is decent enough to give the general idea that a very strong phase 7 doesn't by itself favor a cold SE. Can it still end up cold this time even if it were to end up very strong? Of course it can based on other factors like +PNA and -AO and it may end up cold. But my study says a very strong phase 7 by itself doesn't specifically say it is likely going to get cold in the SE. I think JB and others are misinformed in thinking a very strong MJO by itself screams cold down here.

2. All of my research is based on RMM data due to there being 42 years of readily available data and because we're talking about a projected very strong MJO (4) on the GEFS and still strong (2.5) on the EPS on the RMM (I.e., apples to apples). I still by the way am forecasting it will come in
much closer to the EPS' 2.5 based on GEFS strong tendency to oversimplify. So, that actually may help some for the SE since it wouldn't actually be "very strong" but instead just "strong".

3. I use ATL/SE US because that's what I'm addressing since that's where we live and we want to know how the very strong MJO tends to influence our wx, not Joe Blo in Chicago or NYC. That's what makes the SE "special". And I don't see a statistical credibility issue with just examining the SE US.

4. Possible physical reason per MDA pro mets: very strong MJO favors more warmth from
the tropics lessening Arctic influence.

5. I just talked to MDA met. He agrees totally with my analysis as well as my prediction that the phase 7 peak will be much closer to the EPS' 2.5 than the GEFS' 4.0 due to bias of GEFS way overdoing past MJOs. He also said the projection by the Euro suite is for the MJO to be weak once it gets to phases 8-1-2, which would then favor colder in the SE. That I agree with. So, if the +PNA, -AO, weak MJO phases 8-1-2 were to then coexist, it would then favor a cold SE mid February. Phil has been ontonthis idea. In essence, I think the cold may end up delayed but not denied in the SE. I mainly think that folks are expecting it to occur too soon.
Click to expand...
The central limit theorem posits that a sample size of about 30-40 is adequate to derive statiatically significant relationships between variables, your diagnosis of the MJO doesn't fit that here, if you replicated this with the OMI and VPM MJO indices that are available through NOAA's ESRL you may get different results. The RMM is notoriously noisy and OLR component in the index often causes it to miss and under sample Western Hemisphere events. This bias in the GFS occurs when the MJO is initialized in the Western Hemisphere, it's not applicable in this case. The GFS overamplfies the MJO except in cases like this where the MJO is initialized in the Maritime Continent, I showed you examples from the Kim et al study published just a few years ago that clearly depicted the EPS being completely underdone with the MJO when it's initialized in the Maritime Continent (& this is probably related to its SAS convective parameterization scheme), I strongly suggest you should read that study. You can't deny the fact that the EPS is getting caught with its pants down on the MJO amplitude lately, it had this event barely reaching the western Pacific a few days ago, while the GFS showed an event with 2-3 signs amplitude, why would blindly put that much stock into the EPS given these large recent adjustments in favor of the GFS? Duh, I know we live in the SE US and that this information is most relevant to us, the comment about what's so special here was geared towards why the MJO keeps us warmer when it's strong (irrespective of phase) while others remain cooler, that's very relevant to diagnosing a physical mechanism here that drives this observation, which still hasn't been addressed here. Giving us a bunch of numbers is great and all but where's the beef? Why is it warmer when the MJO is amplified in any phase? You also do realize even if the MJO is in the circle of death, sometimes the EOFs that the real-time data is projected onto fail to capture MJO events, this is why I asked you to explore using other indices. If you could get to the root of this it would make your and MDA's argument a lot stronger.
 
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