Medium Range Discussion Winter 2011-12

[wxmx]

Love it when (presumed) tropical dudes get into icekitty dirty dancing in public.

Well, that's how we noticed yesterday was the coldest day of the winter in Prague.

[HurricaneJosh]

Don't you have some cold temperature obs from Prague to post somewhere?

Well, that's how we noticed yesterday was the coldest day of the winter in Prague.

lolz, perfectly matched responses-- hot off the press. Did you coordinate these?

[donsutherland1]

La Niña Update:

From Message #711 (January 23, 2012):

I don't believe there will be rapid weakening. My guess is that there will be a slow fade during February, possibly with the Region 3.4 anomalies starting out in the -1.2°C to -1.0°C range and ending in the -0.9°C to -0.7°C range.

A slow fade in the La Niña was a core assumption behind my February forecast (#703) that featured widespread warm anomalies across North America.

The weekly ENSO Region 3.4 anomaly centered around February 1 was -1.2°C. That is slightly colder than the -1.1°C figure registered in the weeks centered around January 18 and January 25. To date, 5 of the first 6 days in February saw the SOI < 0 vs. the 8 days in all of January. Hence, the La Niña is about where I expected it to be starting February, though at the bottom of the range. It is probably near or at its peak. Afterward, it should begin to fade, but the fade should be gradual in February. A more rapid weakening could take place in March.

[usedtobe]

Allen doesn't have it broken out by AO phase, but the Nina 1-2 composites are actually warm for the East. 8 is cold, though.

Where is the link to those maps. I used to have it but it disappeared. Now I wish I had downloaded all of them.

[am19psu]

Where is the link to those maps. I used to have it but it disappeared. Now I wish I had downloaded all of them.

http://raleighwx.americanwx.com/MJO.html

[usedtobe]

http://raleighwx.ame...wx.com/MJO.html

Thanks! La NIna Phases 1 and 2 certainnly have a strong postive epo look.

[GaWx]

This MJO wave propagating more like the GFS ensembles became apparent a day or so ago when the IO convection dissapated and the h2 structure was clearly over the eastern most wave. This is legit folks!

What do you get when you get a MJO wave through phase 8-1-2 and a -AO in a La Nina February? I am sure Don has the composites already.

The sample size is small, but I did the analysis for NYC. Since 1975 there have been four significant periods of 8-1-2 (outside the circle of death) during La Nina's that included any part of Feb. The total # of -AO Feb. La Nina 8-1-2 days since 1975 was only ten from the four La Nina 8-1-2 periods:

At NYC: the results were rather intuitive. 5 days were cold, 3 were near normal, and 2 were warm. The ten days averaged 30F or an average of a chilly four below normal for the respective dates. An impressive 5 of the 10 dates had S/IP: 4.3", 3.9", 1", T, and T. This adds to 9.2" or an avg. of ~0.9"/day vs. the longterm Feb. avg. of 0.3"/day. So, the snowfall was about three times the average/day.

Here are the ten La Nina -AO 8-1-2 FEB dates at NYC with high/low/snowfall:

2/6/75: 45/32/T

2/7/75: 42/26/T

2/8/75: 35/21

2/1/76: 47/33

2/2/76: 45/10/1.0"

2/3/76: 27/14

2/1/85: 37/32/3.9"

2/2/85: 35/25/4.3"

2/3/85: 30/19

2/22/99: 27/16

[donsutherland1]

Over the past two days, the GFS ensembles have shifted from a negative to severely negative AO in the extended range to a positive one. In addition, the ongoing La Niña has strengthened somewhat. As a result, I have stronger confidence that any cold that occurs over the next week or so will likely prove transient in North America. Hence, much of North America will likely be milder than normal during the February 16-22 timeframe.

Composite temperature anomalies based on ENSO Region 3.4 anomalies of -1.55°C to -0.70°C, an AO of +0.50 to +1.00, and PNA of 0.00 to +1.00 are below:

In North America, I suspect that readings in Alaska will be near normal to perhaps somewhat below normal. The one change I would make with respect to the chart for Europe is that the cold in Europe would extend eastward from where it is centered, meaning that the eastern sections showing warm anomalies would be cold, as well. The rest of the composite temperature anomalies for North America and Europe appear reasonable.

In sum, any cold in eastern North America will likely remain transient. A cold pattern probably won't lock in.

[GaWx]

Here are some additional relevant stats:

For NYC during La Nina's/MJO of 8-1-2 since 1975 during Jan. and Feb.:

+AO: 28 total days...S/IP of 0.4"/day (~normal) and temp.'s ~normal (one above normal)

-AO: 38 total days....S/IP of 0.9"/day (~3 times normal) and temp.'s four below normal

I consider these results as rather intuitive.

---------------------------------------------------------

+AO dates: 1/19-2/5/1975

2/16-21, 23, 24/1999

1/27-28/2011

-AO dates: 2/6-8/1975

1/27-2/3/1976

1/12-2/3/1985

2/22/1999

1/24-26/2011

[Feb]

Over the past two days, the GFS ensembles have shifted from a negative to severely negative AO in the extended range to a positive one. In addition, the ongoing La Niña has strengthened somewhat. As a result, I have stronger confidence that any cold that occurs over the next week or so will likely prove transient in North America. Hence, much of North America will likely be milder than normal during the February 16-22 timeframe.

Composite temperature anomalies based on ENSO Region 3.4 anomalies of -1.55°C to -0.70°C, an AO of +0.50 to +1.00, and PNA of 0.00 to +1.00 are below:

In North America, I suspect that readings in Alaska will be near normal to perhaps somewhat below normal. The one change I would make with respect to the chart for Europe is that the cold in Europe would extend eastward from where it is centered, meaning that the eastern sections showing warm anomalies would be cold, as well. The rest of the composite temperature anomalies for North America and Europe appear reasonable.

In sum, any cold in eastern North America will likely remain transient. A cold pattern probably won't lock in.

Earlier this winter you didn't believe the GFS Ensembles in regards to what they did with the AO. Why are you buying them now?

[Ellinwood]

Earlier this winter you didn't believe the GFS Ensembles in regards to what they did with the AO. Why are you buying them now?

FWIW, Euro ensembles are showing the same thing.

[donsutherland1]

Earlier this winter you didn't believe the GFS Ensembles in regards to what they did with the AO. Why are you buying them now?

I don't always go against the GFS ensembles and I don't always accept their solution. Nevertheless, they are, on average, a good forecasting tool. In this case, the flip in the GFS ensembles reinforced some of the other guidance that was signaling a return to an AO+. That the GFS ensembles have maintained their new solution has removed some of the uncertainty involved. Prior to the flip in the GFS ensembles, I had considered a much larger AO spread. However, even a modestly negative AO would still have resulted in a generally mild solution, though not as impressive as the most recent data and perhaps a little cooler (closer to normal but still on the mild side of normal in most cases).

[OSUmetstud]

I don't always go against the GFS ensembles and I don't always accept their solution. Nevertheless, they are, on average, a good forecasting tool. In this case, the flip in the GFS ensembles reinforced some of the other guidance that was signaling a return to an AO+. That the GFS ensembles have maintained their new solution has removed some of the uncertainty involved. Prior to the flip in the GFS ensembles, I had considered a much larger AO spread. However, even a modestly negative AO would still have resulted in a generally mild solution, though not as impressive as the most recent data and perhaps a little cooler (closer to normal but still on the mild side of normal in most cases).

Don, I believe the AO will stay negative. I think the models are doing exactly what they were doing earlier this winter, returning the AO to more of a neutral state. The 7 day, 10 day, and 14 day gfs ensemble forecasts have not had the AO negative enough. The strat vortex has been sufficiently destroyed so I don't think we will see a return to positive...probably an ease, though. As you mentioned, the tangible effects may not be all that significant, though.

[TNE]

This MJO wave propagating more like the GFS ensembles became apparent a day or so ago when the IO convection dissapated and the h2 structure was clearly over the eastern most wave. This is legit folks!

What do you get when you get a MJO wave through phase 8-1-2 and a -AO in a La Nina February? I am sure Don has the composites already.

Time to get off that high horse HM before we hit June. I have heard these calls for sustained cold starting from late November. The only thing I remember is having 50s & 60s and plenty of rain throughout this winter. I do not disregard the opportunity of having transient cold air or cold spells no greater than three days behind a cold front ...and there might as well be opportunity to have snow before we get over 32F. We had snow on October 29 with marginal cold air and a superb track, and we had snow with marginal cold air at the 850mb on January 21st. This means it is possible to have snow with marginal cold air and a good storm track, but cold air so far this winter has not been sustained. It lasts for two or three days and then the upper trough lifts out and a High Pressure in the middle of the country takes control and brings warmer air..

Having sustained cold air is the problem and current ensembles once again show the AO on an increase after the episode on the 12-13 of February. Pattern this winter and late fall has been filled with cut-off energy developing around Baja/TX, warming trends and 60s , and transient cold spells during or shortly after the cut-off energy hits the East Coast. It is these cut-off Lows and cold fronts associated with them that cause the exciting weather and the cold spells. All of you get so excited looking at those -21C isotherms going into the East that you forget everything.

Anyways, Models have decent snow potential on the 12-13 with the polar energy diving toward the Atlantic. It is analogous to our past snow events with some cut-off energy moving into the Atlantic and some strong polar air diving toward the East Coast. The key word is transient, and everytime 5-10 days before we have an event like this , mets/weenies are calling for it to bring sustained cold air to our area. Never happens and you might as well call for sustained cold air before we hit summer.

TNE

[Nic]

If fhe PV stays over Hudson Bay, it will keep swinging arctic fronts in the great lakes? Right?

[QVectorman]

Time to get off that high horse HM before we hit June. I have heard these calls for sustained cold starting from late November. The only thing I remember is having 50s & 60s and plenty of rain throughout this winter. I do not disregard the opportunity of having transient cold air or cold spells no greater than three days behind a cold front ...and there might as well be opportunity to have snow before we get over 32F. We had snow on October 29 with marginal cold air and a superb track, and we had snow with marginal cold air at the 850mb on January 21st. This means it is possible to have snow with marginal cold air and a good storm track, but cold air so far this winter has not been sustained. It lasts for two or three days and then the upper trough lifts out and a High Pressure in the middle of the country takes control and brings warmer air..

Having sustained cold air is the problem and current ensembles once again show the AO on an increase after the episode on the 12-13 of February. Pattern this winter and late fall has been filled with cut-off energy developing around Baja/TX, warming trends and 60s , and transient cold spells during or shortly after the cut-off energy hits the East Coast. It is these cut-off Lows and cold fronts associated with them that cause the exciting weather and the cold spells. All of you get so excited looking at those -21C isotherms going into the East that you forget everything.

Anyways, Models have decent snow potential on the 12-13 with the polar energy diving toward the Atlantic. It is analogous to our past snow events with some cut-off energy moving into the Atlantic and some strong polar air diving toward the East Coast. The key word is transient, and everytime 5-10 days before we have an event like this , mets/weenies are calling for it to bring sustained cold air to our area. Never happens and you might as well call for sustained cold air before we hit summer.

TNE

TNE, HM can easily defend his own forecast, but I am just going to say if you review the GWO, MJO, stratospheric warm and AAM all culminate and point to a colder pattern coming up...not just a quick shot of cold air behind a short wave. If you read his prior posts and his thread on the AAM and GWO you can see that. It seems you have not looked beyond the what the models spit out.

[QVectorman]

I normally post over at Westernwx, but I figured the composites I threw together would be more interesting for you guys anyways. These are similar to what Don Sutherland usually posts, and that is because him and I have been in contact for a while now. Just want to say thanks Don for all the help, very much appreciated.

Anyways, here we go. I took a look at the MJO progression, and aside from the Euro, all the models are in pretty good agreement. For those that don't have a link, here's the MJO chart I find the most useful:

http://www.daculawea...se_forecast.php

The below composites are made up from the above image, keeping region, amplitude, and month into consideration. The last image on the bottom-right is the GFS Ensemble analogs rolled forward 3 days, which matches up time wise with the last MJO composite

Pretty good agreement between the MJO composites and the GFS analogs that you guy's might get a chance for some winter weather. One thing that caught my eye today was the fact that the AO forecast had greatly increased compared to previous ones. If it were to verify, the chances and magnitude of cold may not be much at all, but we'll have to wait and see what future run's show. Take it easy everyone

Thanks for the composites, nice work...although from my understanding there is a 10-14 day lag from the time of the phase until the downstream flow affects the continental US. So the 1-5 and 6-10 day composites might be irrelevant, it might be better to do those same composites for the same amplitude but at a 10+ day lag. etc. But I am not sure how much of a lag the CPC uses on their composites. If anyone know that would be awesome...DTK??

[Ji]

how can a model show this on 6z and then the exact opposite a run later

[andyhb]

Possibly because the 06z GFS isn't running on fresh upper air data...

[Ottawa Blizzard]

JB tweeted today that he thinks NYC might get down to 0F next Monday morning.

[thenewbigmack]

Thanks for the composites, nice work...although from my understanding there is a 10-14 day lag from the time of the phase until the downstream flow affects the continental US. So the 1-5 and 6-10 day composites might be irrelevant, it might be better to do those same composites for the same amplitude but at a 10+ day lag. etc. But I am not sure how much of a lag the CPC uses on their composites. If anyone know that would be awesome...DTK??

Thanks for the feedback. I haven't actually heard of the 10-14 day lag time before, so I very well may be wrong. Would be interested to hear how that actually works.

[nzucker]

JB tweeted today that he thinks NYC might get down to 0F next Monday morning.

He has got to be kidding himself...850s aren't even -20C...NYC had 850s around -24C in January 2009 and only made it to 6F.

[donsutherland1]

JB tweeted today that he thinks NYC might get down to 0F next Monday morning.

The last time NYC got to 0°F was January 27, 1994. I don't see anything rivaling the Arctic outbreak responsible for such cold. Prior to the extreme cold in January 1994, much of Canada and Alaska had been experiencing much below normal readings for some time. This time around, most of the extreme cold air is located in Europe and Asia. The severe cold in Alaska is also retreating. If I had to venture a guess, it would be that the temperature would fall to 13°F in Central Park (NYC) on Monday morning, but even that is not assured. A higher reading is plausible.

[dtk]

Thanks for the feedback. I haven't actually heard of the 10-14 day lag time before, so I very well may be wrong. Would be interested to hear how that actually works.

I can't comment specifically on your remark here, but....

To answer qvectorman's question, the methodology for the CPC composites is described in detail here:

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/Composites/Temperature/readme.shtml

[Ottawa Blizzard]

He has got to be kidding himself...850s aren't even -20C...NYC had 850s around -24C in January 2009 and only made it to 6F.

BigJoeBastardi Joe Bastardi

Euro has nice look too at 48, says near 0 NYC Monday am Emperor of the north will lay down his carpet before calling http://pic.twitter.com/hjHbNPty

[HM]

Time to get off that high horse HM before we hit June. I have heard these calls for sustained cold starting from late November. The only thing I remember is having 50s & 60s and plenty of rain throughout this winter. I do not disregard the opportunity of having transient cold air or cold spells no greater than three days behind a cold front ...and there might as well be opportunity to have snow before we get over 32F. We had snow on October 29 with marginal cold air and a superb track, and we had snow with marginal cold air at the 850mb on January 21st. This means it is possible to have snow with marginal cold air and a good storm track, but cold air so far this winter has not been sustained. It lasts for two or three days and then the upper trough lifts out and a High Pressure in the middle of the country takes control and brings warmer air..

Having sustained cold air is the problem and current ensembles once again show the AO on an increase after the episode on the 12-13 of February. Pattern this winter and late fall has been filled with cut-off energy developing around Baja/TX, warming trends and 60s , and transient cold spells during or shortly after the cut-off energy hits the East Coast. It is these cut-off Lows and cold fronts associated with them that cause the exciting weather and the cold spells. All of you get so excited looking at those -21C isotherms going into the East that you forget everything.

Anyways, Models have decent snow potential on the 12-13 with the polar energy diving toward the Atlantic. It is analogous to our past snow events with some cut-off energy moving into the Atlantic and some strong polar air diving toward the East Coast. The key word is transient, and everytime 5-10 days before we have an event like this , mets/weenies are calling for it to bring sustained cold air to our area. Never happens and you might as well call for sustained cold air before we hit summer.

TNE

Did you really need to type 350 words to let us all know you are a douche?

[Chris L]

Did you really need to type 350 words to let us all know you are a douche?

This made me laugh, HM.

You tell 'em.

Anyway, I believe the issue this winter largely is due the block is on the other side of the globe, mostly.

[Met1985]

Did you really need to type 350 words to let us all know you are a douche?

Lol very funny! I love reading your post HM very interesting all the way around and i hope you are right. Still a lot of time left for winter.

[TNE]

Time to get off that high horse HM before we hit June. I have heard these calls for sustained cold starting from late November. The only thing I remember is having 50s & 60s and plenty of rain throughout this winter. I do not disregard the opportunity of having transient cold air or cold spells no greater than three days behind a cold front ...and there might as well be opportunity to have snow before we get over 32F. We had snow on October 29 with marginal cold air and a superb track, and we had snow with marginal cold air at the 850mb on January 21st. This means it is possible to have snow with marginal cold air and a good storm track, but cold air so far this winter has not been sustained. It lasts for two or three days and then the upper trough lifts out and a High Pressure in the middle of the country takes control and brings warmer air..

Having sustained cold air is the problem and current ensembles once again show the AO on an increase after the episode on the 12-13 of February. Pattern this winter and late fall has been filled with cut-off energy developing around Baja/TX, warming trends and 60s , and transient cold spells during or shortly after the cut-off energy hits the East Coast. It is these cut-off Lows and cold fronts associated with them that cause the exciting weather and the cold spells. All of you get so excited looking at those -21C isotherms going into the East that you forget everything.

Anyways, Models have decent snow potential on the 12-13 with the polar energy diving toward the Atlantic. It is analogous to our past snow events with some cut-off energy moving into the Atlantic and some strong polar air diving toward the East Coast. The key word is transient, and everytime 5-10 days before we have an event like this , mets/weenies are calling for it to bring sustained cold air to our area. Never happens and you might as well call for sustained cold air before we hit summer.

TNE

The 00z GFS pushes back the October 29 analog and flirts with the January 21 analog for this winter. As far as I can see (and I am basically copying what happened before and during January 21st), we have a transient cold snap (one or two days below average) and convective snow showers with the polar advances on the 11-14th. Disturbance associated with cut-off energy moving from the west on the 14th, surface Low passes east. 850mb Low warms up everybody up to NYC, MARGINAL & TRANSIENT COLD ONCE AGAIN. Overrunning event mixed with sleet in NYC and coastal areas (minor snowfall accumulations for V-Day), inland areas in PA & CT most likely get the most benefit from this

The winter pattern has been evident since late fall, mets and weenies just kept on thinking it would change. Not gonna happen until we get to March. Let's enjoy these little snow events and cold snaps while it is still possible, but the majority of this winter will be remembered for its warm temperatures. Who can agree you that at THIS POINT IN FEB?

[OHweather]

The 00z GFS pushes back the October 29 analog and flirts with the January 21 analog for this winter. As far as I can see (and I am basically copying what happened before and during January 21st), we have a transient cold snap (one or two days below average) and convective snow showers with the polar advances on the 11-14th. Disturbance associated with cut-off energy moving from the west on the 14th, surface Low passes east. 850mb Low warms up everybody up to NYC, MARGINAL & TRANSIENT COLD ONCE AGAIN. Overrunning event mixed with sleet in NYC and coastal areas (minor snowfall accumulations for V-Day), inland areas in PA & CT most likely get the most benefit from this

The winter pattern has been evident since late fall, mets and weenies just kept on thinking it would change. Not gonna happen until we get to March. Let's enjoy these little snow events and cold snaps while it is still possible, but the majority of this winter will be remembered for its warm temperatures. Who can agree you that at THIS POINT IN FEB?

I agree, the way this winter has gone, we need to take these cold snaps and little snows as they come and enjoy them to the best of our ability.

Oh, and I guess you sort of skipped over the first 29 and a half pages of this thread and jumped right to the GFS. The MJO is the strongest it has been all winter, and looks to have a good chance at propigating all the way into phases 8-1-2 for the first time since November...the stratosphere has significantly warmed...among other things that are over my head, but have been explained by some of the boards most respected red taggers, in this and other threads in the main forum. We have things going on in the tropics and in the stratosphere that have not happened all winter until recently. I don't think we will see the month of February average below normal, I don't think anyone is claiming that...but the chances for appreciable snow appear to be increasing over the east as the month of February progresses. The pattern has changed.