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3/17-3/18 Storm Threat Discussion


Zelocita Weather

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Well to be fair it happened with our Jan/Feb storms too. Last minute north trends that kept trending. Probably nothing this drastic in terms of run to run but we did go from practically nothing to 8-12" in 3 days with the early Feb storm. Unfortunately its doing the reverse this time.

 

What is confusing is that the models sampled the energy so badly to show such an extreme solution and then do a complete 180 as soon as that energy came onshore.

The whole winter has been a mess from 2-3 days out.  General public was caught off guard with the 2/3 event b/c the humans could not keep up with the machines fast enough and the reverse on 3/3-some folks here Sunday night were preparing for snow the next morning.  Been a tough winter in that regard....

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Well to be fair it happened with our Jan/Feb storms too. Last minute north trends that kept trending. Probably nothing this drastic in terms of run to run but we did go from practically nothing to 8-12" in 3 days with the early Feb storm. Unfortunately its doing the reverse this time.

 

What is confusing is that the models sampled the energy so badly to show such an extreme solution and then do a complete 180 as soon as that energy came onshore.

the only model that showed an extreme solution was the GGEM, If you took a blend of the Euro/GFS then there wouldn't be much to expect in the first place. 

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The problem occurs today between hours 30 and 36. Glancing at the GEFS mean you can see it even more clearly.

 

If you look at the 12z NAM, it too runs the southern energy out ahead of the main northern energy running out. That matches the GFS and the GGEM. We'll leave the Euro out of this for now as we await its 12z run.

 

The main differences are really the handling of the northern vort. The 12z NAM at hour 36 has the energy over Colorado and Nebraska. The 12z GEFS mean sends that same energy to Arizona and New Mexico.

 

I wouldn't be overly quick to say that one solution is more favorable here over another.

 

I will admit that I'm personally astounded by the way the GGEM has folded like a cheap suit.

 

The good news is that we'll know by the 12z runs tomorrow at the latest. Everything should be resolved by then. It's pretty clear that if the energy digs like the GFS shows this will be a miss to the south.

 

I believe that it all has to do with just how positive the PNA rises. Per the current ensembles, sounds like the PNA has just about peaked.

 

pna.sprd2.gif

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the only model that showed an extreme solution was the GGEM, If you took a blend of the Euro/GFS then there wouldn't be much to expect in the first place. 

The nam/jma/sref and euro/gfs ensembles all showed at least 6" of snow. Maybe the 12"+ was unlikely but this is looking like we're going to see nothing now

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We will all brush up on our meteoroly, just for you. :hug:

It's been a very changeable winter in terms of storminess, that's what very progressive patterns do. Changes happen quickly when tiny pieces of energy in a extremely fast, chaotic system interact differently here and there. "The butterfly flapping its wings in Brazil" line applies more often than people realize, and we're nowhere close to being able to resolve every perturbation. Try dropping 30 rocks of different sizes into a pond and then forecast the size and consistency of every resulting wake in the water stemming from those disturbances. Not so easy.

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It's been a very changeable winter in terms of storminess, that's what very progressive patterns do. Changes happen quickly when tiny pieces of energy in a extremely fast, chaotic system interact differently here and there. "The butterfly flapping its wings in Brazil" line applies more often than people realize, and we're nowhere close to being able to resolve every perturbation. Try dropping 30 rocks of different sizes and then forecast the size and consistency of every resulting wake in the water stemming from those disturbances. Not so easy.

It's been the most challenging I can remember. No model did well, some did better than others. We saw last minute trends, north, south, weaker, stronger, warmer, colder. Just when you think you've got it figured out it throws you a curve ball. That's why I figure we'll end up with a surprise snowstorm in April when nobody is expecting it. Just to finish off the winter with one final blow to the head lol. Thankfully we can come out of it with a great overall winter with plenty of snow despite all the confusion and headaches from the ones that missed

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It's been the most challenging I can remember. No model did well, some did better than others. We saw last minute trends, north, south, weaker, stronger, warmer, colder. Just when you think you've got it figured out it throws you a curve ball. That's why I figure we'll end up with a surprise snowstorm in April when nobody is expecting it. Just to finish off the winter with one final blow to the head lol. Thankfully we can come out of it with a great overall winter with plenty of snow despite all the confusion and headaches from the ones that missed

That's why I say after early March I usually just want spring. Cold and dry patterns in March are just the absolute worst. I'd much rather have 60s and start looking toward backdoor front season.

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The problem occurs today between hours 30 and 36. Glancing at the GEFS mean you can see it even more clearly.

 

If you look at the 12z NAM, it too runs the southern energy out ahead of the main northern energy running out. That matches the GFS and the GGEM. We'll leave the Euro out of this for now as we await its 12z run.

 

The main differences are really the handling of the northern vort. The 12z NAM at hour 36 has the energy over Colorado and Nebraska. The 12z GEFS mean sends that same energy to Arizona and New Mexico.

 

I wouldn't be overly quick to say that one solution is more favorable here over another.

 

I will admit that I'm personally astounded by the way the GGEM has folded like a cheap suit.

 

The good news is that we'll know by the 12z runs tomorrow at the latest. Everything should be resolved by then. It's pretty clear that if the energy digs like the GFS shows this will be a miss to the south.

 

I believe that it all has to do with just how positive the PNA rises. Per the current ensembles, sounds like the PNA has just about peaked.

 

pna.sprd2.gif

the UUL off the Pac coast is stronger on the GFS which pumps the ridge more causing the n sream disturbance to dive more south then southeast like the Nam

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This last month has been nothing but a tease . So much for that so called great pattern lol.

Great patterns dont always result in snow (personally I dont think this winter had great patterns, we never had a -nao and the PNA was hit ad miss, but thats not a convo for now). Do you think in winters like 1976-77 the pattern wasnt great, at least, at times?

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Even the 12z JMA is south :lol:

 

CONUS_JMA_1000-500_SLPTHKPRP_72HR.gif

 

This reeks of overcorrection, many times I've seen this occur where all models swing one direction one run they often times eventually correct back the other way...we'll see what happens...again much more room for this to re-surface than there was the other event.

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This reeks of overcorrection, many times I've seen this occur where all models swing one direction one run they often times eventually correct back the other way...we'll see what happens...again much more room for this to re-surface than there was the other event.

Agreed, I think it's pre-mature to say this threat is completely gone.

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but the GGEM was consistent....when the GGEM is one showing a solution and the GFS and Euro disagree, the GGEM is WRONG (which it usually is)

Except for two weeks ago when the Euro and GFS were north for many runs and very snowy but the GGEM disagreed. The GGEM turned out to be right. Now the reverse is true, the common denominator being of course the bad solutions winning.

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The 12z runs are the 1st set of runs that have the southern vort fully sampled.

That is already having a clear affect on the whole thing. Started with the NAM (despite people not seeing it) and then clearly on the GFS/UKMET.

I agree. If we don't see major changes at 0z, this one is likely done.

It is not fully sampled. That energy hasn't even come onshore yet. Until it does, we won't know for sure.

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but the GGEM was consistent....when the GGEM is one showing a solution and the GFS and Euro disagree, the GGEM is WRONG (which it usually is)

Except when it isnt.  The verification stats are real, the GGEM has been only behind the Euro this year.  Just because people are mad that it looks like the GGEM was way too bullish on this storm doesn't make this any less so.  

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Agreed, I think it's pre-mature to say this threat is completely gone.

I have to agree, something affected the entire 12z suite and they all made radical changes. I don't know if all the data has been sampled yet but that could play a huge role in this. If there's some data missing right now and then it gets injected into a suite of runs then you might see another radical shift by all the models. These differences are huge because they indicate whether it's a massive storm or barely anything at all.

 

We saw how this data played out with the Boxing Day storm when we all thought it would be a bust. 

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Except for two weeks ago when the Euro and GFS were north for many runs and very snowy but the GGEM disagreed. The GGEM turned out to be right. Now the reverse is true, the common denominator being of course the bad solutions winning.

 

winna winna chicken dinna

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HM from the mid-atlantic thread, a reminder that this storm isn't the same as two weeks ago:

 

 

 

The 12z runs made some subtle long wave changes that affected the way our s/w manifests. Initially, you'll look at the models and say "more energy is hanging back/split off" and really that would be a fine analysis. The issue here is that the subtle changes in the western ridge affects the jet across the northern-tier. Between this process and the slower exit of the PV (which by itself wouldn't be a big deal...but it is a killer in combination with broadening western ridge), the flow speeds up, reducing partial phasing of s/w.

Here's the good news before you start to compare how amazingly annoying that it was the 12z runs 2Fridays ago that also started to shift the storm: that 3/3 system was being punished by a much more wicked PV and lobe dropping down from Ontario. In fact, it pushed in considerable dry and cold air advection throughout the precipitation shield, reducing accumulating snow to just the convergence zones post-initial thump WAA. In this case, despite the 12z shifts, we are still seeing frontogenetic forcing within general WAA across MA. This means, old rules apply about "edge of QPF shield" since that is conveniently placed along the 850mb deformation zone. 

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It's not a matter of disagreement. NCEP model data is available on a hundred different sites, many of which roll out graphics just as fast as—if not faster than—paid services. I completely support accurate descriptions of what a given model has shown, what trends are evident vs. prior runs, initialization vs. current observations, etc., because that's useful. It is extremely confusing and destructive to the integrity of the discussion to repeatedly jump the gun and post misleading speculative one-liners that directly contradict each other. If you're going to say "I see x, and I think that might mean y", that's fine; much of the time it seems like many folks are bent on being the first to acknowledge a frame, though, and as we all know, haste makes waste.

 

It's the same deal with the 12z NAM a few hours ago; I woke up and logged in to the forums on my phone, read through three pages of "wow, what an epic/weenie/HECS run straight out of Anthony's basement!", only to find that the model took significant steps back from a major snow solution. It's confusing, and I would say in direct contrast to the site's mission of disseminating and analyzing info fairly, accurately, and professionally.

 

I don't mean to single anyone out, although there are repeat offenders, and I wish we could do away with the monkey business of forecasting the models. We have all weekend to mull over data... we don't need to risk distributing complete falsities for the sole purpose of blurting out model steps mere seconds before our colleagues. This thread has almost as many guests reading as it does registered users—just keep that in mind.

 

I'll take it to banter or something from here on out, but I feel this needed to be said.

Great post, agree completely. While I do appreciate people taking the time to do pbp, I wish they would only comment on the output they're actually seeing and not speculate on what they think is going to happen next, especially with only a minute or so to even analyze the current frame before the next frame comes out - it's easy to miss things when one doesn't have enough time to critically evaluate what the model is representing. It's far better to be right and a little late than to be wrong, but first.

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