December 2018 General Discussion & Observations

[gravitylover]

Flipped to all snow here a little while ago, down to 33*.

[Gravity Wave]

Moderate snow in Chelsea, my deck has a slushy coating.

[LIWeatherGuy29]

Pouring rain here. It's not too often that the heavy rain band sets up over Nassau County.

[gravitylover]

.2/.3", 33, everything including the street is coated. It's pretty much over now and it looks like winter again.

[Rtd208]

Picked up 0.98" of rain for the day.

Storm total 1.24"

Current temp 38

[doncat]

1.50" for yesterday, 1.79" for the three days and 65.20" for the year... Two or three more good storms, maybe I'll hit 70"

[LibertyBell]

11 hours ago, 40/70 Benchmark said:

1968-1969 is a good ENSO analog....boderline weak/moderate peak, but a meager MEI...thus the season played out more like a weak el nino with late developing Miller Bs.

Ray was there any suppression that season?  Anything like the Carolina crusher that NC had this season?

[LibertyBell]

3 hours ago, Gravity Wave said:

Moderate snow in Chelsea, my deck has a slushy coating.

Looks like the snow made it as far east as Queens.

[CIK62]

Next 8 days averaging 44degs., or about 9degs. AN.

Month to date is  -1.0[38.7].    Should be +2.3[40.5] by the 25th.

EPS has 1" Snow for the next 10 days----but that has already happened.    GEFS is a 75% chance of at least 2" by Jan. 01.

With the current GFS, this month is going to end up at +4 or worse.   Awful look.   Someone is going to get a 70* day late in the month, when even 40 is AN, with this ugly run.

The RRWT isn't even initialized properly and says it is BN now and for the rest of Dec.   Getting more BN in Jan.   Crazy stuff.

[bluewave]

This strong MJO in the milder phases for North America will be one of the major events for December. So far it has resulted in the most positive +EPO reading of 2018 at +257. The big snow cover drop in mid-December is a rare occurrence. It reflects the shift to milder following the colder pattern since late October.

https://www.star.nesdis.noaa.gov/smcd/emb/snow/HTML/snow_extent_plots.html

[frd]

1 hour ago, bluewave said:

This strong MJO in the milder phases for North America will be one of the major events for December. So far it has resulted in the most positive +EPO reading of 2018 at +257. The big snow cover drop in mid-December is a rare occurrence. It reflects the shift to milder following the colder pattern since late October.

@bluewave another nice observation, and I am a bit bummed about losing snowcover , but I bet we rebound going forward. 

A question, is not the very reason for the warm up to a degree, and the decline in snow cover, the very pattern that has and will continue to put pressure on the SPV? 

I read from HM and Isotherm that tropical forcing with regards to weakening and disturbing the PV are just as important as other players. It seems to me the precursor pattern you see in the NE Pac and the Atlantic are all contributing. I read  research about the precursor pattern matching what has happened so far. 

So, do you believe the pattern now and for the next week or two are contributing to the strat warming and the possible SSWE? Thanks as always !! 

[bluewave]

13 minutes ago, frd said:

@bluewave another nice observation, and I am a bit bummed about losing snowcover , but I bet we rebound going forward. 

A question, is not the very reason for the warm up to a degree, and the decline in snow cover, the very pattern that has and will continue to put pressure on the SPV? 

I read from HM and Isotherm that tropical forcing with regards to weakening and disturbing the PV are just as important as other players. It seems to me the precursor pattern you see in the NE Pac and the Atlantic are all contributing. I read  research about the precursor pattern matching what has happened so far. 

So, do you believe the pattern now and for the next week or two are contributing to the strat warming and the possible SSWE? Thanks as always !! 

I posted a few recent papers on the topic last winter. Dr. Amy Butler probably has the best twitter feed on the stratosphere.

https://mobile.twitter.com/drahbutler?lang=en

 

https://ams.confex.com/ams/21Fluid19Middle/webprogram/Paper317541.html

12.2 Teleconnection between Madden Julian Oscillation and Sudden Stratospheric Warmings

More

 

Thursday, 29 June 2017: 10:45 AM

Salon G-I (Marriott Portland Downtown Waterfront)

Wanying Kang, Harvard University, Cambridge, MA; and E. Tziperman

Recorded Presentation

 

Sudden Stratospheric Warming (SSW) events influence the Arctic Oscillation and mid-latitude extreme weather. Observations show SSW events to be correlated with certain phases of Madden Julian Oscillation (MJO), but the teleconnection mechanism, its planetary wave propagation path and the teleconnection time scale are still not well understood. We study the Arctic stratosphere response to MJO forcing using two models. First, a comprehensive General circulation model (the Whole Atmosphere Circulation Model, WACCM) with standard and enhanced convection entrainment rate leading to stronger MJO. Second, an idealized dry dynamical core with and without idealized MJO-like forcing. We show that the frequency of SSW events increases significantly, and that the averaged polar cap temperature therefore increases significantly in response to stronger MJO forcing. Consistent with previous studies, we find that heat transport by stationary waves is a major contributor to the SSW response. We also find that MJO-forced transient waves propagate at about 70 mb toward the Arctic, and then travel toward the upper stratosphere, then leading to the stationary wave response. The cleaner results possible with the idealized model allow us to identify that the propagation time is of the order of 40-60 days, significantly longer than implied by previous studies. The horizontal propagation path is influenced by zonal jet exit regions, again in agreement with previous studies of remote tropospheric effects of MJO-forced planetary waves. Given that MJO is predicted to be stronger in global warming scenario, these results suggest that SSW events may become more frequent in a future warm climate, possibly with all the implications this has on tropospheric high latitude weather.

 - Indicates paper has been withdrawn from meeting

 - Indicates an Award Winner

 

http://onlinelibrary.wiley.com/doi/10.1002/2015GL066984/full

Finally, we reexamine the relationship between SST anomalies and MJO activity based on the historical record. Previously, Hendon et al. [1999] showed enhanced MJO activity, both globally and locally in the western/central Pacific, favored by positive SST anomalies in the central Pacific equatorial region around 160°E–160°W during November–March (their Figure 10).

[frd]

6 minutes ago, bluewave said:

I posted a few recent papers on the topic last winter. 

Thanks for sharing the link and research, and it seems there is a role based on your papers. 

The question at this time are the implications for our areas in general. Maybe more clarity will arrive in a couple weeks.  

[40/70 Benchmark]

26 minutes ago, bluewave said:

I posted a few recent papers on the topic last winter. Dr. Amy Butler probably has the best twitter feed on the stratosphere.

https://mobile.twitter.com/drahbutler?lang=en

 

https://ams.confex.com/ams/21Fluid19Middle/webprogram/Paper317541.html

12.2 Teleconnection between Madden Julian Oscillation and Sudden Stratospheric Warmings

More

 

Thursday, 29 June 2017: 10:45 AM

Salon G-I (Marriott Portland Downtown Waterfront)

Wanying Kang, Harvard University, Cambridge, MA; and E. Tziperman

Recorded Presentation

 

Sudden Stratospheric Warming (SSW) events influence the Arctic Oscillation and mid-latitude extreme weather. Observations show SSW events to be correlated with certain phases of Madden Julian Oscillation (MJO), but the teleconnection mechanism, its planetary wave propagation path and the teleconnection time scale are still not well understood. We study the Arctic stratosphere response to MJO forcing using two models. First, a comprehensive General circulation model (the Whole Atmosphere Circulation Model, WACCM) with standard and enhanced convection entrainment rate leading to stronger MJO. Second, an idealized dry dynamical core with and without idealized MJO-like forcing. We show that the frequency of SSW events increases significantly, and that the averaged polar cap temperature therefore increases significantly in response to stronger MJO forcing. Consistent with previous studies, we find that heat transport by stationary waves is a major contributor to the SSW response. We also find that MJO-forced transient waves propagate at about 70 mb toward the Arctic, and then travel toward the upper stratosphere, then leading to the stationary wave response. The cleaner results possible with the idealized model allow us to identify that the propagation time is of the order of 40-60 days, significantly longer than implied by previous studies. The horizontal propagation path is influenced by zonal jet exit regions, again in agreement with previous studies of remote tropospheric effects of MJO-forced planetary waves. Given that MJO is predicted to be stronger in global warming scenario, these results suggest that SSW events may become more frequent in a future warm climate, possibly with all the implications this has on tropospheric high latitude weather.

 - Indicates paper has been withdrawn from meeting

 - Indicates an Award Winner

 

http://onlinelibrary.wiley.com/doi/10.1002/2015GL066984/full

Finally, we reexamine the relationship between SST anomalies and MJO activity based on the historical record. Previously, Hendon et al. [1999] showed enhanced MJO activity, both globally and locally in the western/central Pacific, favored by positive SST anomalies in the central Pacific equatorial region around 160°E–160°W during November–March (their Figure 10).

I started following Amy last week...great strat. stuff.

[gravitylover]

4 hours ago, CIK62 said:

Next 8 days averaging 44degs., or about 9degs. AN.

Month to date is  -1.0[38.7].    Should be +2.3[40.5] by the 25th.

EPS has 1" Snow for the next 10 days----but that has already happened.    GEFS is a 75% chance of at least 2" by Jan. 01.

With the current GFS, this month is going to end up at +4 or worse.   Awful look.   Someone is going to get a 70* day late in the month, when even 40 is AN, with this ugly run.

The RRWT isn't even initialized properly and says it is BN now and for the rest of Dec.   Getting more BN in Jan.   Crazy stuff.

I'm generally pretty tired of your warm doom and gloom daily posts but I'll happily take a 70* day before the end of the month. I loved that uber warm stretch around Christmas for a couple of years, there's just something great about riding mountain bikes in shorts and t-shirts on (or near) Christmas Eve that I can't quite quantify but it's surely there  

[donsutherland1]

Today marked the 6th consecutive day that the Southern Oscillation Index (SOI) was +10.00 or above. That sets a new record for most consecutive days during which a winter month (December, January, February) had an ENSO Region 3.4 anomaly of +0.5°C or above.  The prior meteorological winter record was 5 consecutive days, which was set in February 2015. The prior December record was 4 consecutive days, which was set in December 2015.

The MJO has also been in Phase 4 with an amplitude of 2.000 or above for 4 consecutive days. No December during which the ENSO Region 3.4 anomaly was +0.50°C or above had more than 2 consecutive such days. 3 prior Decembers had 2 consecutive days meeting such criteria: December 2002, December 2006, and December 2015. December 2006 was the only December case that saw such an MJO coincide with a positive SOI.

In short, the current global synoptic setup is a highly anomalous event.

If some of the ensembles are right, this setup should breakdown over the next 7-10 days. The SOI could go negative toward the latter part of that timeframe. The MJO will likely move into Phase 5 at a fairly high amplitude toward the latter part of that timeframe. While some previuos guidance had suggested a low amplitude outcome, a low amplitude appears very unlikely to verify over the next 10 days and probably longer.

The last time the MJO had an amplitude below 1.000 was October 30. To date, the MJO has had an amplitude of 1.000 or above for 46 consecutive days. During winter 2007-08, the MJO had a high amplitude for 69 consecutive days. The meteorological winter record is 78 consecutive days set during the December 13-Feburary 28, 2018 period (with the MJO finally moving into low amplitude on March 13, 2018 after 90 consecutive days at high amplitude).

The ongoing rare MJO-SOI events will lead to a lot of uncertainty for perhaps the next several weeks. Nevertheless, even as the last week of December now looks below average in terms of prospects for accumulating snow in the northern Middle Atlantic region (some but not a high possibility exists), the base case going forward appears to be the following:

1. The ocean and atmosphere will likely couple (probably in January) leading to the atmosphere's becoming consistent with the ongoing El Niño.
2. The MJO will remain at high amplitude through the remainder of December as it progresses into Phase 5 and then Phase 6. It will likely move into the colder Phases in January.
3. The warm SSTAs in the Gulf of Alaska will lead to the decay and breakdown of the ongoing EPO+, but that will probably happen during the first half of January, consistent with a similar evolution of events in winter 2002-03.
4. The PDO has gone positive in December after a somewhat negative November (based on daily data). Some caution is advised, as daily data was used. The JSAO.Washington.edu PDO page has not been updated recently (its last monthly value was +0.09 for September). A positive PDO has typically been present during snowy El Niño winters.

Overall, it still appears likely that winter 2018-19 will wind up snowier than normal in the Great Lakes region, Middle Atlantic region, and southern New England. However, the risk of significant snowfall will likely remain below average until January. Northern New England could provide an exception.

As for December in New York City, the statistical probability of December's being warmer than normal has increased dramatically in recent days. The implied probability is now 74% based on sensitivity analysis. The implied monthly mean temperature is 38.1°-39.4° (normal: 37.5°).

 

[Brasiluvsnow]

I posted this elsewhere I meant to put it here, If the mods want to delete one feel free--->I know that people are making and have plans and will want to know what the weather will be like as far as traveling ( maybe someone would see fit to begin a thread on Xmas holiday travel weather ? ) --> I just looked at this upcoming weekend and a few models have a big wet mess for Friday and Saturday = again thats wet NOT white. Then I looked and it seems some models still have a" possible" White system around the 24th and yes still plenty of time thats a week away.

[doncat]

3 hours ago, gravitylover said:

I'm generally pretty tired of your warm doom and gloom daily posts but I'll happily take a 70* day before the end of the month. I loved that uber warm stretch around Christmas for a couple of years, there's just something great about riding mountain bikes in shorts and t-shirts on (or near) Christmas Eve that I can't quite quantify but it's surely there  

Agree with the daily doom and gloom, geez. I remember last  year at this time we were watching a bitter arctic air mass coming southward and trying to time out its arrival. Some modeling had it arriving shortly after Christmas with a very mild Xmas day...Well  Xmas was cold in the 30's and shortly thereafter we dropped below freezing and stayed there for two weeks.

[forkyfork]

17 hours ago, forkyfork said:

look at the moisture feed on friday. more records to fall

[Juliancolton]

47 minutes ago, forkyfork said:

I like the >1.8" PWATs.

[LongBeachSurfFreak]

9 minutes ago, Juliancolton said:

I like the >1.8" PWATs.

Snow pack destroyer for the mountains. Right in time for Christmas week...

[AfewUniversesBelowNormal]

6 hours ago, donsutherland1 said:

Today marked the 6th consecutive day that the Southern Oscillation Index (SOI) was +10.00 or above. That sets a new record for most consecutive days during which a winter month (December, January, February) had an ENSO Region 3.4 anomaly of +0.5°C or above.  The prior meteorological winter record was 5 consecutive days, which was set in February 2015. The prior December record was 4 consecutive days, which was set in December 2015.

The MJO has also been in Phase 4 with an amplitude of 2.000 or above for 4 consecutive days. No December during which the ENSO Region 3.4 anomaly was +0.50°C or above had more than 2 consecutive such days. 3 prior Decembers had 2 consecutive days meeting such criteria: December 2002, December 2006, and December 2015. December 2006 was the only December case that saw such an MJO coincide with a positive SOI.

In short, the current global synoptic setup is a highly anomalous event.

If some of the ensembles are right, this setup should breakdown over the next 7-10 days. The SOI could go negative toward the latter part of that timeframe. The MJO will likely move into Phase 5 at a fairly high amplitude toward the latter part of that timeframe. While some previuos guidance had suggested a low amplitude outcome, a low amplitude appears very unlikely to verify over the next 10 days and probably longer.

The last time the MJO had an amplitude below 1.000 was October 30. To date, the MJO has had an amplitude of 1.000 or above for 46 consecutive days. During winter 2007-08, the MJO had a high amplitude for 69 consecutive days. The meteorological winter record is 78 consecutive days set during the December 13-Feburary 28, 2018 period (with the MJO finally moving into low amplitude on March 13, 2018 after 90 consecutive days at high amplitude).

The ongoing rare MJO-SOI events will lead to a lot of uncertainty for perhaps the next several weeks. Nevertheless, even as the last week of December now looks below average in terms of prospects for accumulating snow in the northern Middle Atlantic region (some but not a high possibility exists), the base case going forward appears to be the following:

1. The ocean and atmosphere will likely couple (probably in January) leading to the atmosphere's becoming consistent with the ongoing El Niño.
2. The MJO will remain at high amplitude through the remainder of December as it progresses into Phase 5 and then Phase 6. It will likely move into the colder Phases in January.
3. The warm SSTAs in the Gulf of Alaska will lead to the decay and breakdown of the ongoing EPO+, but that will probably happen during the first half of January, consistent with a similar evolution of events in winter 2002-03.
4. The PDO has gone positive in December after a somewhat negative November (based on daily data). Some caution is advised, as daily data was used. The JSAO.Washington.edu PDO page has not been updated recently (its last monthly value was +0.09 for September). A positive PDO has typically been present during snowy El Niño winters.

Overall, it still appears likely that winter 2018-19 will wind up snowier than normal in the Great Lakes region, Middle Atlantic region, and southern New England. However, the risk of significant snowfall will likely remain below average until January. Northern New England could provide an exception.

As for December in New York City, the statistical probability of December's being warmer than normal has increased dramatically in recent days. The implied probability is now 74% based on sensitivity analysis. The implied monthly mean temperature is 38.1°-39.4° (normal: 37.5°).

 

To add to the anomalous nature of this, subsurface warm pool below Nino 3.4 is strengthening. This is a strengthening El Nino signal that historically has higher pressure correlation in the Northern Hemisphere than SOI, Nino 3.4 SSTs, and even MEI, in now-time. 

[AfewUniversesBelowNormal]

4 hours ago, forkyfork said:

Some models have 500mb closing near the Gulf of Mexico, as a larger system. I wonder how many times that has happened in December? 

[bluewave]

49 minutes ago, AfewUniversesBelowNormal said:

Some models have 500mb closing near the Gulf of Mexico, as a larger system. I wonder how many times that has happened in December? 

Not too many. Models are going for a -5.29 sd 500 mb anomaly over the GOM. That would be one of the strongest on record for late December.

http://cms.met.psu.edu/sref/GFS/

[IntenseBlizzard2014]

1 minute ago, bluewave said:

Not too many. Models are going for a -5.29 sd 500 mb anomaly over the GOM. That would be one of the strongest on record for late December.

http://cms.met.psu.edu/sref/GFS/

I noticed that we are breaking a lot of records recently. Maybe the YTD Rainfall is next? 

[MJO812]

Weeklies look awesome

[Brasiluvsnow]

46 minutes ago, Snow88 said:

Weeklies look awesome

88 how so ? share with the group lol

[MJO812]

Just now, Brasiluvsnow said:

88 how so ? share with the group lol

Cold but we know they can change

Everyone is on board with a big pattern change by the 1st week of January.

I wouldn't discount snow for xmas. Still have to watch it.

Mjo is on the move.

Get some sleep

[Brasiluvsnow]

16 minutes ago, Snow88 said:

Cold but we know they can change

Everyone is on board with a big pattern change by the 1st week of January.

I wouldn't discount snow for xmas. Still have to watch it.

Mjo is on the move.

Get some sleep

88 thanks , is there somewhere that a person ( me ) can see the weeklies or are they only on pay sites ? 

[donsutherland1]

47 minutes ago, Brasiluvsnow said:

88 thanks , is there somewhere that a person ( me ) can see the weeklies or are they only on pay sites ? 

They are only on a paid site. However, the 500 mb pattern evolves toward the classic EPO-/AO- pattern shown in the chart for my winter thoughts.

https://www.americanwx.com/bb/topic/51728-winter-outlook-2018-2019/