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Pattern February Discussion Part II

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ATLwxfan said:
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Let's go positive trends. I need to break this bad boy in.


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SD said:
He's going to need it didn't you see the gfs? Leading the way with this. Euro is trash

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I think it's time to start the thread on this and call it : Feb 10 Storm, Could Be Rain, Could Be Snow, Could Be Dry!?
 
The chance is there that the GFS is off of course but it did kind of lead the way last time. It's solution was wrong but it was closer than the Euro was for a while, for a while the Euro effectively showed nothing outside of the mountains in Georgia and that wasn't the case.

The GEFS isn't great but it's increased in members that has shown actual weather from this, we'll just need to wait and see what happens.
 
Here is my new video that I just recorded. What this looks like to me is that there is a phase with that weak disturbance and with a low poping up on the frontal boundary.

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Thanks for the video, Don.
What will the 0Z GFS have around 2/13-16? The 18Z GFS was quite cold for 2/14-5. Prelim maps are suggesting that the peak PNA ridge MAY setup a little west of earlier runs. If so, if the corresponding E US trough is also a little west but still as deep, perhaps that would allow some moisture to be in the picture. Let's see what it shows.
 
I think the snow in Mexico has just returned on this run.

And there it is...it's back but it a different way.
 
Looks like we may have some indices cooperating a little better between the 15th and 20th:

4indices.png


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I can’t believe I didn’t catch the mid-latitude SSW > tropical convection/MJO connection earlier… An ongoing sudden stratospheric warming event (SSWE) induced via wave 2 polar vortex split, w/ simultaneous upper level ridging over the far North Atlantic and North Pacific is potentially contributing to the initiation of an Madden Julian Oscillation (MJO) event in the Maritime Continent and far western Pacific. The stratospheric warming event aids in triggering the MJO event via enhanced wave driving in the mid-latitudes and a stronger than normal meridional overturning circulation. The invigorated meridional circulation induces large-scale upwelling in the near-equatorial stratosphere and upper troposphere, and is augmented by mass and water-vapor convergence in the lower troposphere. This leads to local cooling in the upper troposphere and stratosphere, thus altering (lowering) the static stability of the upper troposphere such that a kelvin-wave like response with deep convection in the tropics is generated. This Kelvin Wave like response and deep tropical convection triggered in part by the high latitude SSWE can also influence the probability of sudden stratospheric warming events by modulating the placement, intensity, and frequency of mid-latitude rossby waves and wave trains which upwell near the stratospheric surf zone and deposit their momentum onto the mean background flow (which envelopes the wintertime polar vortex). Therefore, although the stratosphere and troposphere are generally referred to as separate entities with their own quasi-independent internal variability, they are actually tightly coupled, and it’s paramount to closely monitor both in order to increase the accuracy and lead time of medium and long range weather forecasts.

You can see the tropical stratosphere respond relatively quickly following the initiation of warming in the mid-upper stratosphere, with fairly significant cooling occurring over the equator... In short, this cooling of the lower stratosphere and upper troposphere induced by the mid-latitude stratospheric warming event and enhanced meridional circulation associated with it decreased the stability of the troposphere, helping to instigate ascent and convection in the troposphere. Hence, a few days later, to no surprise, an MJO event developed in the Maritime Continent and Western Pacific. We also had simultaneous stratospheric warming events in the northern and southern hemispheres earlier this fall aid in the instigation of a series of CCKWs and MJO events over the Maritime Continent and Western Pacific. Interesting huh?...

20S-0S longitudinal average temperature-height cross section time series. Note the downward propagation of negative temperature anomalies from the upper stratosphere to the lower stratosphere and upper troposphere in conjunction with the SSWE occurring simultaneously in the arctic...
Screen Shot 2017-02-05 at 11.19.16 AM.png

Zonally averaged 100mb (lower stratosphere) latitude-T time series. Note the cooling near the equator that followed the stratospheric warming in the high-latitudes of the northern hemisphere...
Screen Shot 2017-02-05 at 11.18.59 AM.png


Here's a relatively simple "hand-wavy" depiction of the Brewer-Dobson Circulation so you can visualize some of the physical processes and connections linking the mid-latitude stratospheric warming event to the recent development of an MJO pulse and CCKW couplet in the tropics... Increased descent in the mid-high latitudes needs to be compensated for by increased upwelling from the tropical troposphere, which leads to the excitation of tropical convection...

image001.jpg


For more information on the stratospheric warming - tropical tropospheric convection, see:
http://onlinelibrary.wiley.com/doi/10.1029/2006GL028744/full
https://www.jstage.jst.go.jp/article/sola/7/0/7_0_197/_pdf
http://journals.ametsoc.org/doi/pdf/10.1175/JCLI3251.1
http://www.ann-geophys.net/34/331/2016/angeo-34-331-2016.pdf

The combination of a Pacific MJO event and intrinsic variability within the high latitude north Pacific, wherein classic retrogression of a northeast Pacific blocking ridge, will lead to the formation of an unusually deep Aleutian-Gulf of Alaska vortex by next week and into at least mid-February. Such a pattern is often characterized by an extensive, eastward displaced, and stronger than normal pacific jet with the majority of the North America continent (except perhaps for the southern tier of the US) usually being flooded with mild, pacific air, and a robust western hemisphere subtropical jet.

eps_z500a_5d_nh_61.png

Regression of the MEI index onto northern hemisphere geopotential heights in February
65.191.40.95.35.9.31.46.gif

Hence, higher than normal risks for above normal precipitation and seasonable temperatures can be expected in the southeastern US for mid-February. Thereafter uncertainty remains with regards to the downward propagation of anomalous stratospheric circulation anomalies in the northern hemisphere exciting a potentially significant high-latitude blocking episode later in the month of February and into early March. The continuation of the MJO pulse from the central Pacific into the Indian Ocean, and a major reshuffling of the equatorial pacific with the possibility for the formation of a downwelling oceanic kelvin wave in the wake of the ongoing MJO pulse. It’s worth mentioning that, in the past 150 years of the observational record, we have yet to observe an El Nino event in year +2 following the culmination strong-super El Nino event, if an El Nino somehow developed next year it would be unprecedented since at least the early 19th century. Oth, this response shouldn’t be too surprising given AGW is likely allowing the Indo-West Pacific warm pool to recover more quickly than the it used to, and the observational record is too short to observe and analyze the full spectrum of ENSO variability…
 
Webberweather53 said:
I can’t believe I didn’t catch the mid-latitude SSW > tropical convection/MJO connection earlier… An ongoing sudden stratospheric warming event (SSWE) induced via wave 2 polar vortex split, w/ simultaneous upper level ridging over the far North Atlantic and North Pacific is potentially contributing to the initiation of an Madden Julian Oscillation (MJO) event in the Maritime Continent and far western Pacific. The stratospheric warming event aids in triggering the MJO event via enhanced wave driving in the mid-latitudes and a stronger than normal meridional overturning circulation. The invigorated meridional circulation induces large-scale upwelling in the near-equatorial stratosphere and upper troposphere, and is augmented by mass and water-vapor convergence in the lower troposphere. This leads to local cooling in the upper troposphere and stratosphere, thus altering (lowering) the static stability of the upper troposphere such that a kelvin-wave like response with deep convection in the tropics is generated. This Kelvin Wave like response and deep tropical convection triggered in part by the high latitude SSWE can also influence the probability of sudden stratospheric warming events by modulating the placement, intensity, and frequency of mid-latitude rossby waves and wave trains which upwell near the stratospheric surf zone and deposit their momentum onto the mean background flow (which envelopes the wintertime polar vortex). Therefore, although the stratosphere and troposphere are generally referred to as separate entities with their own quasi-independent internal variability, they are actually tightly coupled, and it’s paramount to closely monitor both in order to increase the accuracy and lead time of medium and long range weather forecasts.

You can see the tropical stratosphere respond relatively quickly following the initiation of warming in the mid-upper stratosphere, with fairly significant cooling occurring over the equator... In short, this cooling of the lower stratosphere and upper troposphere induced by the mid-latitude stratospheric warming event and enhanced meridional circulation associated with it decreased the stability of the troposphere, helping to instigate ascent and convection in the troposphere. Hence, a few days later, to no surprise, an MJO event developed in the Maritime Continent and Western Pacific. We also had simultaneous stratospheric warming events in the northern and southern hemispheres earlier this fall aid in the instigation of a series of CCKWs and MJO events over the Maritime Continent and Western Pacific. Interesting huh?...

20S-0S longitudinal average temperature-height cross section time series. Note the downward propagation of negative temperature anomalies from the upper stratosphere to the lower stratosphere and upper troposphere in conjunction with the SSWE occurring simultaneously in the arctic...
View attachment 17

Zonally averaged 100mb (lower stratosphere) latitude-T time series. Note the cooling near the equator that followed the stratospheric warming in the high-latitudes of the northern hemisphere...
View attachment 18


Here's a relatively simple "hand-wavy" depiction of the Brewer-Dobson Circulation so you can visualize some of the physical processes and connections linking the mid-latitude stratospheric warming event to the recent development of an MJO pulse and CCKW couplet in the tropics... Increased descent in the mid-high latitudes needs to be compensated for by increased upwelling from the tropical troposphere, which leads to the excitation of tropical convection...

image001.jpg


For more information on the stratospheric warming - tropical tropospheric convection, see:
http://onlinelibrary.wiley.com/doi/10.1029/2006GL028744/full
https://www.jstage.jst.go.jp/article/sola/7/0/7_0_197/_pdf
http://journals.ametsoc.org/doi/pdf/10.1175/JCLI3251.1
http://www.ann-geophys.net/34/331/2016/angeo-34-331-2016.pdf

The combination of a Pacific MJO event and intrinsic variability within the high latitude north Pacific, wherein classic retrogression of a northeast Pacific blocking ridge, will lead to the formation of an unusually deep Aleutian-Gulf of Alaska vortex by next week and into at least mid-February. Such a pattern is often characterized by an extensive, eastward displaced, and stronger than normal pacific jet with the majority of the North America continent (except perhaps for the southern tier of the US) usually being flooded with mild, pacific air, and a robust western hemisphere subtropical jet.

View attachment 19

Regression of the MEI index onto northern hemisphere geopotential heights in February
View attachment 20

Hence, higher than normal risks for above normal precipitation and seasonable temperatures can be expected in the southeastern US for mid-February. Thereafter uncertainty remains with regards to the downward propagation of anomalous stratospheric circulation anomalies in the northern hemisphere exciting a potentially significant high-latitude blocking episode later in the month of February and into early March. The continuation of the MJO pulse from the central Pacific into the Indian Ocean, and a major reshuffling of the equatorial pacific with the possibility for the formation of a downwelling oceanic kelvin wave in the wake of the ongoing MJO pulse. It’s worth mentioning that, in the past 150 years of the observational record, we have yet to observe an El Nino event in year +2 following the culmination strong-super El Nino event, if an El Nino somehow developed next year it would be unprecedented since at least the early 19th century. Oth, this response shouldn’t be too surprising given AGW is likely allowing the Indo-West Pacific warm pool to recover more quickly than the it used to, and the observational record is too short to observe and analyze the full spectrum of ENSO variability…
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Webb - Very informative and thanks! I've been saying that the Pac was the driver and you have provided some in-depth analysis as to why that's the case!
PS - The graphics really assist in understanding - thanks for including those, BTW!
 
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SD said:
Cmc is pushing 80 in some locations next Saturday

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CMC is the new Euro! Leading the way! A lot of people dismissed it the last few days when it showed a very warm solution, now GFS is headed that way! Congrats on the sleet, atleast you got two events this winter, now that spring is here for good! :(
 
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