Winter 2014-2015 Pattern Discussion Thread I

[LithiaWx]

Let's talk about the AO. I want to flush this out and learn why some think I'm wrong. Like I said if I am I'll gladly admit so. I see an area of lower 500mb heights centered right over the Davis strait on the 18z GFS ensemble that was posted a few times. A -AO would feature higher heights there is what I understood. What am missing here? The Atlantic doesn't look very cooperative on that map. Nothing to lock in storms like a 50/50 or amped up heights blocking up the pattern. It doesn't have the look I'm accustomed to seeing in a -NAO and -AO regime.

[WxKnurd]

http://www.nc-climate.ncsu.edu/climate/patterns/NAO.html

Read to your hearts content. -AO image/diagram looks pretty familiar doesn't it?

[GaWx]

Let's talk about the AO. I want to flush this out and learn why some think I'm wrong. Like I said if I am I'll gladly admit so. I see an area of lower 500mb heights centered right over the Davis strait on the 18z GFS ensemble that was posted a few times. A -AO would feature higher heights there is what I understood. What am missing here? The Atlantic doesn't look very cooperative on that map. Nothing to lock in storms like a 50/50 or amped up heights blocking up the pattern. It doesn't have the look I'm accustomed to seeing in a -NAO and -AO regime.

 

Marietta,

 The -AO features higher than normal 500 mb heights over the Arctic, which is centered further north than the ~65-70 N of the Davis Straight.

[LithiaWx]

http://www.nc-climate.ncsu.edu/climate/patterns/NAO.html

Read to your hearts content. -AO image/diagram looks pretty familiar doesn't it?

  

Marietta,

 The -AO features higher than normal heights over the Arctic, which is centered further north than the ~65-70 N of the Davis Straight.

So it's weak to slightly negative AO? The signal isn't strong correct? Or is it being dampened out due to being an ensemble? Isn't there black and white number that could be posted that correlate to this time frame? Someone mentioned they had them but didn't want to post them.

[Jon]

  

So it's weak to slightly negative AO? The signal isn't strong correct? Or is it being dampened out due to being an ensemble? Isn't there black and white number that could be posted that correlate to this time frame? Someone mentioned they had them but didn't want to post them.

18z GFS ens mean AO goes neutral the 19th and hits -1 by the 22nd, ensemble spread from +0.5 to  -3

[LithiaWx]

As for Kirk Mellish's forecast that is LCs near exact wording and Kirk posted that around 10am this morning. After LC released his. I agree if his is what it appears to be someone has some splainin to do.

[Wow]

It's not just merely unprofessional, it's outright plagiarism & is pushing awfully close into legal territory in terms of copyright infringement, especially if he copies from a private company/weather firm for example... Even if by chance what he's doing isn't illegal it's completely dishonest, shameful, and is a breach of unwritten ethical standards. 

 

Robert had asked me about him when he did it the first time back last January and told him to drop a line to ask for credit where credit is due in his article since this was from paid subscriber material, and if he did it again then drop him from his service.  He had cut stuff out of DT's writeups as well from that January mishap.

[LithiaWx]

18z GFS ens mean AO goes neutral the 19th and hits -1 by the 22nd, ensemble spread from +0.5 to  -3

I stand corrected about the AO. My bad saying it looked like a +AO. That's obviously not correct. I have plenty of learning to do like many people. I'm far from perfect and being humbled from time to time is never a bad thing. I'll learn from this and have greater knowledge moving forward. Thank you all for the lesson about a key teleconnection.

[DaculaWeather]

The last three paragraphs are almost word for word what Larry Cosgrove wrote yesterday Lol. I mean like copy and paste word for word. Maybe I am missing something cause i was reading it on my phone but it looks like Cosgrove's article from yesterday

Wouldn't be the first time that Melish has been caught plagiarizing. He was caught twice last year copying Robert's stuff.

[franklin NCwx]

Strong signal for a storm on the ensembles around day 9-10.

[mackerel_sky]

Haven't seen anything about the Euro, was it that bad or staying the course, from last night?

[Southern Track]

Funny no one mentioned the cut off low spinning into the SE at the end of the 0z. Euro

[CAD_Wedge_NC]

Funny no one mentioned the cut off low spinning into the SE at the end of the 0z. Euro

Are you referring to the 5 contour cut-off low in south GA. Yep I saw it. I am taking a wait-and-see approach with this one. The Euro has a known bias when it comes to cut-offs. However, that would be nice if it verified.

[Shack]

Looks like the GFS caught a similar strain of flu as that of the Euro.

00z takes the 500 low over NE at 120hrs and pushes it southeast.

And the Doc holds serve on this idea.

 

Those of you more adept at the analysis, is this something as unusual as it appears to me? Even possible?

 

And, both have the cutoff over the southwest at day 7, but the cold still looks marginal, and the wonkiness of the whole thing past day 4 looks like my mother-in-law's therapeutic paintings she did while in the psych ward.

[Southern Track]

Are you referring to the 5 contour cut-off low in south GA. Yep I saw it. I am taking a wait-and-see approach with this one. The Euro has a known bias when it comes to cut-offs. However, that would be nice if it verified.

Yeah that's the one.  I assumed since it was 240 hours out, and, like you said, the Euro loves spitting out cut-offs at the end of it's runs, that it didn't get alot of buzz.

[packbacker]

Starting day 8 the southern cut off tries to phase with a strong cut off over the lakes...cut offs everywhere.  I didn't know the Euro had a bias towards cutoffs.

 

 

 

Snow down in central/south GA...2m's are two warm but interesting.  

 

[mackerel_sky]

There's always a Great Lakes low to mess everything up! All the cold in SE Canada looks ready to tap in the future!

[packbacker]

Haven't seen anything about the Euro, was it that bad or staying the course, from last night?

 

The Euro is slower moving the low over the Alaska west then the GFS/GEM.  The GEM is the boldest, GFS is in the middle and the Euro is the slowest with that, been that way.  Still looks fine, things still moving in the right direction.

[franklin NCwx]

Euro has a bias of leaving troughs in the sw.

As far as the storm the ensembles have a strong signal for one. Whether it's a cutoff,snow storm or just rain is yet to be determined.

[griteater]

The Euro is slower moving the low over the Alaska west then the GFS/GEM.  The GEM is the boldest, GFS is in the middle and the Euro is the slowest with that, been that way.  Still looks fine, things still moving in the right direction.

That's how I see it too Pack.  As far as western ridging / eastern troughing, GEM looks the best, then GFS, then Euro on the ensembles.  Still baby steps at this point.

 

As far as the storm the ensembles have a strong signal for one. Whether it's a cutoff,snow storm or just rain is yet to be determined.

That's a good looking southern stream wave

[griteater]

Per the GFS, this is where we will be on Dec 15th with regard to Dec surface temperature anomalies (map is month to date + 7 day forecast) - so, it looks close to normal when including all of the southeast - above in western areas

 

[burgertime]

Starting day 8 the southern cut off tries to phase with a strong cut off over the lakes...cut offs everywhere.  I didn't know the Euro had a bias towards cutoffs.

 

 

 

 

Snow down in central/south GA...2m's are two warm but interesting.  

 

 

 

The Euro seems to default to big cutoffs in the LR for some reason. Last night's run was a perfect track for an ULL for us. I would love for that to happen but I've seen it depicted a bunch on the Euro already and including last winter. Probably not going to happen. 

[franklin NCwx]

Per the GFS, this is where we will be on Dec 15th with regard to Dec surface temperature anomalies (map is month to date + 7 day forecast) - so, it looks close to normal when including all of the southeast - above in western areas

interesting, and with the ensembles showing a colDer pattern after that it looks like we could finish the month below average.

[Amos83]

I stand corrected about the AO. My bad saying it looked like a +AO. That's obviously not correct. I have plenty of learning to do like many people. I'm far from perfect and being humbled from time to time is never a bad thing. I'll learn from this and have greater knowledge moving forward. Thank you all for the lesson about a key teleconnection.

 

Hey Marietta, don't feel too bad... I was reading the maps wrong myself and was coming up with a similar conclusion on the state of the AO as you were. Glad you asked the question so now we both have learned something! This is why I keep most of my opinions to myself and just lurk around

[Cold Rain]

Per the GFS, this is where we will be on Dec 15th with regard to Dec surface temperature anomalies (map is month to date + 7 day forecast) - so, it looks close to normal when including all of the southeast - above in western areas

My -1 call for December may not end up looking too bad.

Edit: At the end of November, based on what was showing up then, one would have expected much more above normal anomalies to exist over the east. Not much torching going on so far (in the east).

[franklin NCwx]

From HM in the mid atlantic thread.

With the arrival of the insane Pacific Jet this week, it will kick off a parade of southern stream lows--one after another. Models, especially ensemble means, will average this out in the day 10-15 period and make it look like some "3-wave configuration" etc. But in reality, a classic PNA, split flow will develop and models will screw-up this separation (especially the GFS). So, expect continued correcting from a smoother, longer wavelength to a shorter wavelength/split stream from the day 10-15 means to day 6-10 means.

There is NO torch coming and eventually these monster southern lows will pay off...

[packbacker]

From HM in the mid atlantic thread.

With the arrival of the insane Pacific Jet this week, it will kick off a parade of southern stream lows--one after another. Models, especially ensemble means, will average this out in the day 10-15 period and make it look like some "3-wave configuration" etc. But in reality, a classic PNA, split flow will develop and models will screw-up this separation (especially the GFS). So, expect continued correcting from a smoother, longer wavelength to a shorter wavelength/split stream from the day 10-15 means to day 6-10 means.

There is NO torch coming and eventually these monster southern lows will pay off...

 

That's good to hear!

[FallsLake]

Per the GFS, this is where we will be on Dec 15th with regard to Dec surface temperature anomalies (map is month to date + 7 day forecast) - so, it looks close to normal when including all of the southeast - above in western areas

 

 

That matches a lot of the analog years. **Looks right for my area but I would have thought the western part of NC would have been below normal. They have been most effected by the CADs.

[Webberweather53]

Let's talk about the AO. I want to flush this out and learn why some think I'm wrong. Like I said if I am I'll gladly admit so. I see an area of lower 500mb heights centered right over the Davis strait on the 18z GFS ensemble that was posted a few times. A -AO would feature higher heights there is what I understood. What am missing here? The Atlantic doesn't look very cooperative on that map. Nothing to lock in storms like a 50/50 or amped up heights blocking up the pattern. It doesn't have the look I'm accustomed to seeing in a -NAO and -AO regime.

 

 

See my post (#1360) in the blog which goes in detail with the physical mechanisms that are driving this pattern rather than just simply looking at the model guidance...

 

Here's the December regressed pattern for the -AO (so yes you would actually be correct on the part where the strongest correlations to the AO are actually in & around the Davis Straits/Greenland. Essentially, the NAO is just a more localized version of the AO index, hence both are often in tandem with each other... (Another note: Difference between correlation & regression is essentially that the regressed composites are indicative of actual patterns that have occurred in the past which in this case represent the index you've chosen)

 

Directly comparing to the NAO, you can see they don't differ by much, if anything as I mentioned above, the NAO is just a localization of the AO, & you should notice both exhibit the strongest correlations in height anomalies over the North Atlantic 

 

You can go to this site that I've pulled these pictures from to analyze correlations & regressions of a wide variety of atmospheric teleconnections (like the AO, NAO, PNA, AAO, MEI, SOI, NH Snowcover Area, QBO, Solar Flux. etc.). You can also lag or lead the composites relative to the variable you're analyzing to the right of where it says "Enter year range of correlations" , which is useful for to detect certain ongoing patterns w/ significant lead time. The patterns shown are also the positive phase of the index you've chosen, in order to show the negative phase simply reverse the color table in the section labeled plot options. You can also change the area of the world you're viewing with plot/region and type or even customize it to fit your own needs, thus you'll need to enter the longitudinal/latitudinal ranges under the section labeled "If CUSTOM or CROSSECTION". Overriding the contour interval (just above reversing the color table) is also useful to check for the strength of correlations to certain variables (i.e. keeping the same contour interval for multiple plots of the same variable, you should often notice the contour interval changes as you change your plot) & you can do this by simply entering in the interval & range (almost always positive & negative values) at which you'd think fits best...

 

http://www.esrl.noaa.gov/psd/data/correlation/

 

I can't stress enough how our SST configuration with the SST twin tripoles in the Atlantic & Pacific is a textbook signature for the -AO. The summarization & simplification what I was saying in that previous post was by raising the SSTs in & around the 40N latitudinal band you're inducing & feeding back to stronger than normal subtropical highs, which regardless of the southern stream, force the jet to remain generally locked further north than usual. Also, because by warming the mid-latitudes & subsequently cooling or at least holding the SSTs steady further north, you are increasing the meridional SST gradient, & we should know that wind is created by temperature differences, by increasing those differences through warming the mid-lat SSTs for example, you are increasing the wind (or the mid-latitude jet stream), a stronger wind & jet stream is directly related to the distance it travels around the northern hemisphere. By consideration of angular momentum, stronger mid latitude jet stream generally=less distance traveled, a retreated jet & thus a +AO/stronger polar vortex & vis versa for the -AO phase...

 

Of course there are other conditions to consider, & in some years the -AO SST correspondence isn't so obvious, but this year is anything but, & it is a gimme as far as I'm concerned. Probably one of the strongest -AO SST signals you may ever see in advance of a winter.... Here is the winter SST correlation to the -AO, you can see it's blatantly obvious this year is closely following this configuration, so you can conclude we're likely about to encounter a predominantly -AO regime 

 

 

 

We can even look @ the NAO...

 

This year Oct-Dec thus far...

[Snowless in Carrollton]

Atlanta is running 11 degrees above normal so far this month. Any chance Atlanta ends the month +5 above normal ?