Winter 2014-2015 Pattern Discussion Thread I

[GaWx]

Fwiw (mainly entertainment and the record), the 18Z GFS has Arctic air coming in on Christmas. Yay

[Bob Chill]

Fwiw (mainly entertainment and the record), the 18Z GFS has Arctic air coming in on Christmas. Yay

Keep watching the nw canada/ak/pole ridge on all guidance. 18z was the most anomalous so far. Great for cold delivery. All of the coldest 12z gefs members had a version of that.

Ensemble means can't show it late in the run with the spread but some cookies are being dropped right now. If ensembles trend towards that type of look as we roll forward it will relieve some nerves around here. Mine included. At least temps and available cold wouldn't be a glaring issue.

[BIG FROSTY]

Keep watching the nw canada/ak/pole ridge on all guidance. 18z was the most anomalous so far. Great for cold delivery. All of the coldest 12z gefs members had a version of that.

Ensemble means can't show it late in the run with the spread but some cookies are being dropped right now. If ensembles trend towards that type of look as we roll forward it will relieve some nerves around here. Mine included. At least temps and available cold wouldn't be a glaring issue.

Thanks for the update, and I appreciate your posts!!!   Around Christmas give or take a day or two, looks pretty good for Cold and possible storm, from what I've been reading!

[Bob Chill]

Thanks for the update, and I appreciate your posts!!!   Around Christmas give or take a day or two, looks pretty good for Cold and possible storm, from what I've been reading!

 

15 day op runs can be full of hurt feelings but the idea is out there and is slowly gaining support. 

 

The 12z run had the same idea but not nearly as amplified as the 18z

 

18z is definitely over done (or easily flat out wrong) but you can see how that type of ridging can punch cold right down on top of us

 

 

The 12z gefs mean trended towards a more similar look today but it's much smoother of course. All we can do is keep an eye out and hope for the best. Should be much clearer by the weekend. 

[WidreMann]

I ask this every winter, but why are we looking at the 384 hour GFS at all?

[Cold Rain]

I ask this every winter, but why are we looking at the 384 hour GFS at all?

I can take this one! Because every frame prior to that sucks. We gotta take the cold where we can get it man.

[JoMo]

I ask this every winter, but why are we looking at the 384 hour GFS at all?

 

Because most people here probably like winter weather, and there is nothing to really look at other than rain in the nearer terms. 

[pcbjr]

I ask this every winter, but why are we looking at the 384 hour GFS at all?

 

Probably for much the same reason as small kids wait up for Santa, until of course, they fall asleep.

[franklin NCwx]

I ask this every winter, but why are we looking at the 384 hour GFS at all?

some of us only look at ensembles past day 7.

Why do you comment on the 10 day op euro?

[packbacker]

I can take this one! Because every frame prior to that sucks. We gotta take the cold where we can get it man.

LOL! Well hour 312 on the GEFS looks good through end of run. Does that count?

[Cold Rain]

LOL! Well hour 312 on the GEFS looks good through end of run. Does that count?

Only if it is the 18z ensembles.

[Bob Chill]

Only if it is the 18z ensembles.

They look pretty good.

[SN_Lover]

NAO going more neutral in the GFS ensembles allowing for heights to lower in the trough in the SE CONUS. Polar vortex remains in Siberia. 

[Cold Rain]

They look pretty good.

Yes they do! Now let's keep the momo going....

[Webberweather53]

Most people including me don't understand what the last couple sentences said. Most of us can hardly read a model let alone try and pick up on Synoptics. Model watching is about as good as us weenies can do.

Alright alright, we get that you put more thought into it than simply model watching which is for peons. Most of us are aware it's guidance. But there is such a thing in seeing trends in the models, without having to look at the "shifting core of upward motion associated w/ tropical forcing in the Pacific enhancing what is already a conducive ENSO base state (+ENSO) & an amplified subtropical jet." We know, you can infact "go on & on...", trust me, we know. But for people who want to post ensemble members and stare at them for days, let them. It's like you're calling out people for not being specific or in-depth enough with their reasoning. I say let people post what they want to post, as long as it's weather related and models, it belongs here. For a lot of us, the MJO charts and composites get old and boring after a while...we want something tangible, and for us that's model output. We're not all mets here and a lot of us are amateur forecasters. We simply don't have the textbook knowledge drilled into our brain to look elsewhere. I mean we can, but by the time we write something up and do all the research it will be January already. Appreciate your input but I think this post was a little much.

Agreed. I mean I could go look at that stuff, but when they're posting it in the main thread and webber is updating in here, what's the need? Model watching isn't bad and please, continue. That's what leads to discussion and thought provoking posts in this sub forum. Alright I'm off my soap box now.

 

Model watching isn't bad? Yeah, ok... It's actually not too complicated when you do a little digging into what's going on & I'll do my best to thoroughly explain things so we're hopefully on the same page...

 

All that was said in the last two sentences was by shifting the mean upward motion associated w/ the upward phase of the MJO (i.e. rising air) further east into the Pacific enhances the base state (or background, ambient, or current state, choose whatever term you like, they have the same meaning) of the ENSO index. Of course, we're currently in an El Nino, which means we should see an eastward shift in the mean convective signal in the Pacific & in the Walker Cell. The Walker Cell involves near surface easterly trade winds blowing warm water over the equatorial Pacific westward & piling it up against the eastern side of the Maritime Continent (Maritime Continent= the islands, including New Guinea, Philippines, Indonesia, etc.), forming the west Pacific warm pool. This warmer water warms the air above it, causing the air to rise (because it's more buoyant, i.e. has a stronger tendency to rise than the surrounding air) & this is termed as Bjerknes feedback where the Sea Surface Temperatures feedback to upward motion. This air rises, cools, & hits the tropopause (boundary between the lowest layer of the atmosphere the troposphere & the layer above it, the stratosphere) because the reaction of ultraviolet radiation from the sun with "normal" oxygen (O2) releases twin & highly reactive single oxygen atoms (2O) that quickly react w/ other ambient (pre-existing) "normal" oxygen in the atmosphere, to form ozone (O3). This process releases heat into the surrounding air, thus the temperature warms w/ increasing height in the stratosphere. This makes it a relative stable layer in the atmosphere (or stably stratified, hence the origin of the term "stratosphere"), lacking a lot of vertical motion & exchange of air because the coolest & densest air within the stratosphere is already laying underneath the comparatively warmer air that lays above it, thus it would make absolutely no sense for it to rise... so we can denote this layer of the atmosphere as one that lacks vertical (upward motion). (In summary warm over cold=stable, cold over warm=unstable) This also means that as convection/thunderstorms, etc. from the troposphere start to interact with the stratosphere where the temperatures warm with height because of ozone, the air eventually reaches a point where it is no longer warmer than the air above it, & hence it stops rising, and spreads out...

 

Over time this air which interacted w/ the lowest layer of the stratosphere, cools, eventually enough to the point to where it sinks back down towards the lower troposphere, re-heating once again along the way... As it hits the impenetrable surface of the earth, it too must spread out (it wouldn't make sense for the air to continue to descend through the earth's solid surface) & because it is now located closer to the surface, it is exposed to a larger fraction of re-emitted long wave infrared radiation (heat) that is directly reflected back towards space by earth's surface as it receives the initial shortwave radiation from the sun. This causes the air closer to the surface to warm once again, eventually forming a simplistic convective cell, which over the tropical Pacific is called the Walker Cell. Once the easterly propagating trade winds that are maintaing the lower portion of the Walker Cell closer to earth's surface slacken, there's no longer anything to hold back the accumulated warm water in the west Pacific warm pool thus, it sloshes back eastward within the equatorial counter current that flows generally along the equator in the opposite direction of the easterly trade wind flow in the  form of equatorially-trapped Oceanic Kelvin Waves. The Kelvin waves suppress the 20C thermocline in the central-eastern Pacific, causing warm water from the warm pool to rush to the east in their wake. This now means the waters are warmer in the central-eastern Pacific & are closer to if not in some cases exceeding ~27-28C (a critical threshold where in latent heat processes (referring to condensation water vapor->liquid), as a consequence, now the upward motion in the lower portion of the Walker Cell shifts east...

 

 

This eastward shift in the mean center of convection & Walker Cell partially due to changes in SSTs also leads to am eastward shift in upper level divergence that originates from this convection... 

(Blue/Purple= anomalous upper level divergence, equates to rising air underneath, Yellow/Orange/Red= anomalous upper level convergence, equates to sinking air underneath)

 

 

The coincident upper level zonal wind anomalies (notice the belt of +anomalies from around Hawaii to Mexico & into the southern US, that's an indication of a stronger than normal subtropical jet)

 

For the purpose of simplicity, treat the dynamical zonal circulation of the MJO like a transient (short-term/temporary) version of the Walker Cell... 

 

What do you think is going to happen when the upward phase MJO shifts into the Pacific lines up w/ the lower frequency upward portion of the Walker Cell & thus briefly amplifies it? (i.e. all I'm referring to here is the timescale of the MJO & Walker Cell, changes & adjustments in the Walker Cell happen on longer timescales than the MJO, thus it's exhibits lower frequency variability).

...You'll see an amplification of an already extensive/stronger than normal subtropical jet stream which is exactly what's happening right now...

 

On the contrary, the El Nino MJO 500mb composites constructed by Allan Huffman are actually tangible. I think there's some confusion over the desired specificity here, you're not supposed to hunt down specifics in a pattern at a range exceeding 5-7 days+ anyway, these composites which give you basic ideas in a certain preset of conditions are applicable. The Central Pacific-Western Hemisphere phases of the MJO (phases 7-1) for December show profound undercutting by the subtropical (southern) branch of the jet, denoted by the lower heights in the Gulf of Alaska "bleeding" into the southern tier of the US (in blue) underneath a belt of relatively formidable belt of higher pressures further to their north doesn't differ too greatly from the current model guidance projections, it's entirely valid.

Now, for those who would like to strengthen their meteorological knowledge basis &/or are frustrated by solely relying upon & being continuously let down by model guidance time & time again (esp. w/ medium-long range forecasting), the very first step to overcoming this barrier is to use the model guidance more sparingly. If you would rather prefer to remain a weather weenie for the rest of your days, which is entirely your choice, then don't adhere to this tidbit of advice & information I've presented in this post. Simple as that...

[superjames1992]

I ask this every winter, but why are we looking at the 384 hour GFS at all?

 

Because it's entertaining and it's fun.  And it's free.  Free and fun!  The perfect duo!

[franklin NCwx]

Webber!

[JoMo]

 

Lots of text.....

 

 

So I'm looking at the latest MJO plots and I'm not seeing where it goes into the 'good' phases at all? Looking at the latest bias corrected ensemble plots, it drops into the COD, and possibly comes back out in phase 4. The longer range Euro plot from the weeklies goes through 3-6 over the next month. Are the models going to be wrong?

[jburns]

Hey Webber.  Great post.  A paragraph now and then would really help the readability.  

[BIG FROSTY]

I like Joe D'Aleo head lines yesterday!

 

You can see above agreement on the +PNA, -AO, -NAO developing as we head towards the cold, snowy late December and January and February.

[Bob Chill]

Because it's entertaining and it's fun. And it's free. Free and fun! The perfect duo!

It's our creed. Coldest and snowiest 24/7 regardless of logic. Haha

In my weenie defense....I posted the lr gfs op panels for the sole purpose of pointing out things to look for. Ensembles are great tools but the smoothing takes away from sensible wx examples. Op runs show good snapshots of how it would look if it was short leads. I know everyone knows this but I'm definitely not a 384 hour verbatim weenie. But that doesn't mean I won't look....because it's too free and fun!

[POWERSTROKE]

I like Joe D'Aleo head lines yesterday!

You can see above agreement on the +PNA, -AO, -NAO developing as we head towards the cold, snowy late December and January and February.

Falls in line with what they've said for months

[Webberweather53]

Hey Webber.  Great post.  A paragraph now and then would really help the readability.  

 

Thanks, I consistently have had trouble in the past dividing up my posts & ending certain thoughts, will try to make corrections to this in the future. I can't help it though when someone says they "don't understand" what I wrote. At that point, I feel obligated to help them out & get down/start with the "understood" basics and work up from there, in the hope that they are nudged just a bit closer to my level of thinking when it's all set & done... 

[calculus1]

Snip...

 

On the contrary, the El Nino MJO 500mb composites constructed by Allan Huffman are actually tangible. I think there's some confusion over the desired specificity here, you're not supposed to hunt down specifics in a pattern at a range exceeding 5-7 days+ anyway, these composites which give you basic ideas in a certain preset of conditions are applicable. The Central Pacific-Western Hemisphere phases of the MJO (phases 7-1) for December show profound undercutting by the subtropical (southern) branch of the jet, denoted by the lower heights in the Gulf of Alaska "bleeding" into the southern tier of the US (in blue) underneath a belt of relatively formidable belt of higher pressures further to their north doesn't differ too greatly from the current model guidance projections, it's entirely valid.

 

Now, for those who would like to strengthen their meteorological knowledge basis &/or are frustrated by solely relying upon & being continuously let down by model guidance time & time again (esp. w/ medium-long range forecasting), the very first step to overcoming this is barrier to use the model guidance more sparingly. If you would rather prefer to remain a weather weenie for the rest of your days, which is entirely your choice, then don't adhere to this tidbit of advice & information I've presented in this post. Simple as that...

 

Webber, that was a fantastic post that you just made.  I personally learned a lot from it.  Thanks for the very detailed explanations.

 

I picked out a couple of nuggets (one practical and one more philosophical) bolded above that I feel are well-worth highlighting, especially for the benefit of those that may not have persevered to the end of the post:

 

First, I am fully on board with the belief that the operational model output does seem to be basically useless beyond day 5 or so.  The ensemble means of each model, however, provide a clearer picture of the type of upper air pattern that could be expected beyond that time frame, but they should never be used to pinpoint a specific storm, much less a location down to the nearest mile or so.  Your use of a variety of different indices and indicators as a complement to the ensemble model output is something of which many of us just do not have a good working knowledge.  As such, we are indebted to your willingness to write and explain it all in a clear and concise manner.

 

Second, you provide an antidote for those seeking a way to escape the emotional roller coaster that is the "sport of weather-model watching."  It's good advice for many who participate in this forum, but, as you said, you can't force somebody to adhere to these suggested guidelines, even though many would be wise to do so.

 

I hope you continue to post here, because I am learning a lot from your shared knowledge.  I would echo jburns' request that you add a little more paragraph structure, but I'll still read even if you don't.  Thanks again.

[WidreMann]

Thanks, I consistently have had trouble in the past dividing up my posts & ending certain thoughts, will try to make corrections to this in the future. I can't help it though when someone says they "don't understand" what I wrote. At that point, I feel obligated to help them out & get down/start with the "understood" basics and work up from there, in the hope that they are nudged just a bit closer to my level of thinking when it's all set & done...

Thoughts on the MJO's impending death?

[NCSNOW]

Don't sweat it webber. Brick encountered the same issues when he first started posting on eastern. It'll come...

Seriously thanks for your efforts. I as others I'm sure enjoy your post. Always a pleasure to get someone who uses synoptics as their main ingredient when trying to dissect and forecast the weather

Can't wait till we get 72 hours from a true threat this year. Your skills will be much appreciated. Be warned though the weenies will show up by the 100 when burger does his pbp.

[jburns]

Thanks, I consistently have had trouble in the past dividing up my posts & ending certain thoughts, will try to make corrections to this in the future. I can't help it though when someone says they "don't understand" what I wrote. At that point, I feel obligated to help them out & get down/start with the "understood" basics and work up from there, in the hope that they are nudged just a bit closer to my level of thinking when it's all set & done... 

 

Keep in mind that it doesn't have to be grammatically correct here.  As far as readability goes, its all visual.  Just make a paragraph every three or four sentences and it will really help.

[deltadog03]

GFS looks like TRASH tonight with that system early next week.  I HIGHLY doubt that system is just gonna go poof...

[mackerel_sky]

Still showing the pattern change at day 14-15?

[Webberweather53]

Thanks calculus 1, NCSNOW, & others...

 

I'm glad you enjoyed the post & grasped my main points despite my usual lengthy post.

 

As for Widremann & others who would like to know my thoughts on this...

 

Simply put, (relatively speaking) the MJO's "impending death" has to do w/ a multitude of factors. OLR E hem bias, (Outgoing Longwave Radiation=OLR, clouds act as a barrier for the OLR to space & thus block it, but because the SSTs are cooler in the western hemisphere & are not as sufficiently high to generate & maintain latent heat processes, there's an overall lack of cloudiness, (although signals in upper level winds still remain) and because OLR is involved in the EOFs of one of the principal components that measures the RMM MJO index, RMM (which is used by CPC for ex) has a tendency to miss on quite a number of MJO events in the western hemisphere, whereas the VPM index that was developed in part by Dr. Mike Ventrice which measures upper level velocity potential instead of OLR, often has a better handle on MJO amplitude in this region of the globe)

 

However, as I mentioned a few days ago, destructive interference (decoupling) of the CCKW & MJO (w/ suppressed phase of CCKW coinciding w/ the upward phase of the MJO) would likely cause a reduction in amplitude of the MJO because the CCKW of all equatorial waves tends to contribute most significantly to the cloudiness, showers, convection, & winds that comprise the MJO (also their similar structures & propagation speeds (@ times I should say) make the CCKW a good candidate for influencing the MJO & it's not  unusual as we're seeing at the present time, to find the RMM indices projecting the MJO as a moist CCKW. Luckily for the global models, which are often way too fast w/ the MJO to begin with, this plays right into their hands & a faster MJO as is typical in an El Nino event, would tend to *reduce* (not necessarily prelude or prevent) model error w/ MJO forecasting & you won't here any complaining from me about this...

 

Strong Mixed-Rossby Gravity Waves & Rossby Waves, which unlike the MJO & CCKW have larger zonal wave numbers (i.e. which is related to their smaller spatial scale & by referring to "wavenumber" I essentially mean that if you happen to recall from general physics, wavelength is denoted by going from one point on a wave (like it's crest for example. to another point that's in exactly the same position on an adjacent wave (or wave that's next to it), thus from one wave crest to an adjacent wave crest is one wavelength, having 2 wave crests or troughs is called wavenumber 2.

 

In terms of equatorial waves (or actually in general as it pertains to meteorology), the more alternating suppressed/convectively enhanced phases you have of a certain wave type, the higher its wavenumber (if you count the number of convectively active phases for example of the MJO & you see that there's one decaying over the central Pacific & another over the western Indian Ocean (a classic phase 1 MJO by the way), you have a zonal wave number of 2 because you have 2 convectively active phases & suppressed phases near the equatorial region ongoing at the exact same time. Thus you can conclude since the zonal (east-west) scale of the equatorial region is finite (limited, or has a set value), the higher the wavenumber of an equatorial wave, the shorter it's wavelength must be.

 

Since these larger wavenumber & shorter wavelength Mixed-Rossby Gravity & Rossby Waves propagate & disburse their energy in a more meridional (north-south) fashion, they are naturally a disruption to the MJO's mean zonal signal, in spite of this however, the MJO is it's still there IMO. If the RMM diagrams show MJO re emergence into the eastern hemisphere within the next few weeks it would clearly be caused by the CCKW, not the MJO, because the MJO simply doesn't propagate at those kinds of speeds (nor does it have the capability to do so as it is at least somewhat limited by the wave filtering techniques that are applied for its detection in the intraseasonal band (30-60+ day)...