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Pattern Jarring January

Wow, the 0Z Euro has Brent's town go below 32 Tue AM and not come back above through the end of the run (Fri evening)! I guess it is his town's turn for historic cold durations.
 
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GFS 6z still very dry for next weeks Tues/Weds threat. Gets some sprinkles going around 19th or so
 
1300m said:
Whoops! That was not on purpose to try to skew the results haha. I went back and corrected that one. That one wouldn't really be classified as a neg. west-based NAO either. Obviously, any sort of negative NAO is not a requirement (far from it) for getting wintry weather in the south, but I'd still prefer to have one as the height configuration is such that it promotes quasi-continuous confluence over the northeastern U.S./southeastern Canada and a suppressed H5 flow that increases the probability of southern U.S. winter storms. We work with all sorts of modified regimes (like the one we just had) which can effectively do the same thing, but to me the west-based neg. NAO is the gold standard in getting the cold ingredients lined up in a workable fashion. It doesn't always work, as it can lead to too much suppression but often it does help set the stage for wintry weather.
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You really want a classic west based -NAO to get Miller A cyclones in the Carolinas and Georgia, split flow upstream in the North Pacific is all we really typically need to get big widespread overrunning events in the SE US. In cases where we are lucky enough to have both present we tend to see hybrid Miller type A and B storms here in the Carolinas. Negative NAO doesn't hurt at all but the missing piece we've had this year is getting an active southern stream and s/ws to dig into California and the Baja. The -EPO/+TNH combo we most often see in these overrunning events is the worst pattern to get a s/w into California and the Baja unfortunately but when it does happen we're in amazing shape. We walk a fine line wrt ENSO and the amount of blocking upstream in the NP and prevalence of the SE Canada vortex...
 
I think too much emphasis is put into individual indicators whether it be teleconnections, ENSO, MJO, QBO, Strat Warming, etc... It always seems that one becomes the dominant signal for a season, and then everyone jumps on the bandwagon and puts too much emphasis in that signal in future years. Consequently, other signals are missed or overlooked.

I do feel that what happens in the Pacific really drives the amount of precip for the SE at the very least. The temperature scheme can be influenced in many other ways.
 
packfan98 said:
I think too much emphasis is put into individual indicators whether it be teleconnections, ENSO, MJO, QBO, Strat Warming, etc... It always seems that one becomes the dominant signal for a season, and then everyone jumps on the bandwagon and puts too much emphasis in that signal in future years. Consequently, other signals are missed or overlooked.

I do feel that what happens in the Pacific really drives the amount of precip for the SE at the very least. The temperature scheme can be influenced in many other ways.
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Yeah I kind of agree. What I have noticed is that there is kind of this tendency to get excited when there is a -AO or get disappointed when there is a neutral NAO and so on. The value of a specific index in isolation doesn't tell you very much about what type of pattern you can expect. Sure, you can dig into data and pull out how this phase of an index correlates to this phase of another index or this type of pattern or what have you. But back in the real world, these "indexes" operate over a fairly expansive domain. The shape, configuration, location, and intensity of these anomalies matter just as much as their sign.

It also matters which other drivers are impacting the pattern. It's extremely complicated. You can pretty well say (if you look historically) that a -AO correlates fairly well with a -NAO. But a west-based -NAO influences the pattern differently than an east-based -NAO. And what if, for example, you have a +PNA plus a -AO plus a west-based -NAO? Arctic cold pattern, right? Well, what if the bitterly cold Arctic air has previously been evacuated to the other side of the globe? It all matters.

I like to put together those silly index reports and post them. And while there is some meager entertainment value there and the index values are important to note, it's just as important to look at their configurations as they relate to each other as well as to observe the overall 500mb pattern so that we can get a true sense as to what the result of a given amalgamation of indexes will be.
 
Rain Cold said:
Yeah I kind of agree. What I have noticed is that there is kind of this tendency to get excited when there is a -AO or get disappointed when there is a neutral NAO and so on. The value of a specific index in isolation doesn't tell you very much about what type of pattern you can expect. Sure, you can dig into data and pull out how this phase of an index correlates to this phase of another index or this type of pattern or what have you. But back in the real world, these "indexes" operate over a fairly expansive domain. The shape, configuration, location, and intensity of these anomalies matter just as much as their sign.

It also matters which other drivers are impacting the pattern. It's extremely complicated. You can pretty well say (if you look historically) that a -AO correlates fairly well with a -NAO. But a west-based -NAO influences the pattern differently than an east-based -NAO. And what if, for example, you have a +PNA plus a -AO plus a west-based -NAO? Arctic cold pattern, right? Well, what if the bitterly cold Arctic air has previously been evacuated to the other side of the globe? It all matters.

I like to put together those silly index reports and post them. And while there is some meager entertainment value there and the index values are important to note, it's just as important to look at their configurations as they relate to each other as well as to observe the overall 500mb pattern so that we can get a true sense as to what the result of a given amalgamation of indexes will be.
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This is why I say that the various indices should be looked at together and also treated as tools instead of as crystal balls. There certainly are fairly significant tendencies that make them more than worthwhile to follow to at least give general odds of what or what does or doesn't lie ahead. In combination, they help to establish what past seasons are good analogs and which aren't. Analogs don't predict the future but they help to establish odds.
 
GFS kind of more robust with the TX moisture around the 17th. Hopefully there will be some cold left , if this comes East
 
The GFS is almost always overzealous with medium-long range warming in the stratosphere, I take its forecasts beyond day 3-4 with a huge grain of salt. If you think tropospheric forecasts are bad, the stratosphere is even worse
 
Tarheel1 said:
GFS kind of more robust with the TX moisture around the 17th. Hopefully there will be some cold left , if this comes East
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Nice rainy sprinkles on 18th! We suck at snow
 
CMC has near zero here on 17th
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Tarheel1 said:
Nice rainy sprinkles on 18th! We suck at snow
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What? Had a historic snow in early December for parts of the southeast followed by last week's historic so ter storm for the SE coast . Now looking at another winter storm for parts of the southeast Friday. And possible light snow for some next week. Yeah that really sucks....

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Storm5 said:
What? Had a historic snow in early December for parts of the southeast followed by last week's historic so ter storm for the SE coast . Now looking at another winter storm for parts of the southeast Friday. And possible light snow for some next week. Yeah that really sucks....

Sent from my SM-J320VPP using Tapatalk
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If yo live between Lithia GA and RAH, outside the mountains it's sucked balls! How much has Birmingham had this year!
 
The 12Z GFS reverses recent trends and is not as cold as recent GFS runs late next week because the cold ends earlier.
 
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