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February Forecast Discussion


REDMK6GLI

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You speak in definitive terms and that is a huge problem for forecasting. What you're looking at is a forecast by an operational model. And what you have to understand is that these models are for guidance. There is no way you can say for sure that the GFS, ECMWF, CMC, whatever will have the correct depiction of the Polar Vortex at this range and the tilt/orientation of it can change in 24 hours. And then suddenly the entire basis of your forecast is wrong.

 

Common sense tells us that there will be a gradient developing as the Polar Vortex retreats, the Southeast Ridge amplifies, and a trough swings down into the SW United States. But what is to say that the Polar Vortex can't retreat farther north? What makes you so sure that the warm air advection can't push northward, that the surface low can't strengthen in the Western Arklatex along a frontal zone and then cut inland? There is minimal blocking.

 

I'm not forecasting any specific outcome at this range, just trying to make a point. You can't say anything definitive at this range -- the best idea is to use ensemble guidance and spaghetti plots to try and observe the trends moving forward and get the best idea as to where we're headed. This could still be a blizzard for Chicago or a KU for all of us.

Well said!

WX/PT

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All the maps show a tremendous area of confluence just south of Greenland near or just north of the Canadian Maritimes and stretching west across much of Canada. This supports arctic high pressure locked in over Ontario and Quebec and a more suppressed storm track, not a cutter. The maps which show the cutters show (I think in error) high pressure over Greenland retreating and the confluence breaking down slightly, but not enough to really buy these solutions. I think we will see more suppressed/benchmark solutions as we move forward, though I would not be shocked if the Euro threw a cutter at us on today's 12Z run.

WX/PT

Thanks for the great input. I think if we had more mets chiming in on these events we would see a lot less bickering.

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You speak in definitive terms and that is a huge problem for forecasting. What you're looking at is a forecast by an operational model. And what you have to understand is that these models are for guidance. There is no way you can say for sure that the GFS, ECMWF, CMC, whatever will have the correct depiction of the Polar Vortex at this range and the tilt/orientation of it can change in 24 hours. And then suddenly the entire basis of your forecast is wrong.

 

Common sense tells us that there will be a gradient developing as the Polar Vortex retreats, the Southeast Ridge amplifies, and a trough swings down into the SW United States. But what is to say that the Polar Vortex can't retreat farther north? What makes you so sure that the warm air advection can't push northward, that the surface low can't strengthen in the Western Arklatex along a frontal zone and then cut inland? There is minimal blocking.

 

I'm not forecasting any specific outcome at this range, just trying to make a point. You can't say anything definitive at this range -- the best idea is to use ensemble guidance and spaghetti plots to try and observe the trends moving forward and get the best idea as to where we're headed. This could still be a blizzard for Chicago or a KU for all of us.

:clap:

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I understand all of your points, I just think at this time the majority of the guidance points away from a cutter.

Yanks i totally understand your firm explanation on forecast runs and i think you dont mean to make it sound definitive from outside of 96 hours especially with how poor modeling this year has been. Earthlight was just trying to make a clarifying statement. You've done a great job with play-by-play lately and give great insight.

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Yanks i totally understand your firm explanation on forecast runs and i think you dont mean to make it sound definitive from outside of 96 hours especially with how poor modeling this year has been. Earthlight was just trying to make a clarifying statement. You've done a great job with play-by-play lately and give great insight.

Thanks, I'm quite confident on this being a blockbuster event, whether it be rain, snow, ice or a mix. Perhaps overly confident. A lot of that has to do with the models and ensembles picking it up at such a long range and for the most part, not wavering much.

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I understand all of your points, I just think at this time the majority of the guidance points away from a cutter.t

If you send multiple weaker impulses out of the pandhandle  then they are pos tilted and will come east of the mountians

any bundling of the energy  the trough sharpens and they cut out of the ozarks 

Waaaaaay to early to know . The set up is such that there`s prob enough confluence to have weaker waves 

belly under . over the next 5 days the models will have to figure out the PV placement  .

But any strong impulse will cut without strong  blocking .  0z Euro OP send the energy out in pieces

The Ensembles are on our side at day 8 -  but thats a long way off in a complicated  pattern 

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The difference between todays 12z Euro at 72 hours and last nights 00z Euro at 84 hours should speak volumes as to the variability among operational models. I suggest you all save yourself some time and energy and wait for ensemble means over the next few days.

Im waiting till post super bowl to take the models seriously. Too much volatility to take a forecast 5-6 plus and run with it.
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You speak in definitive terms and that is a huge problem for forecasting. What you're looking at is a forecast by an operational model. And what you have to understand is that these models are for guidance. There is no way you can say for sure that the GFS, ECMWF, CMC, whatever will have the correct depiction of the Polar Vortex at this range and the tilt/orientation of it can change in 24 hours. And then suddenly the entire basis of your forecast is wrong.

 

Common sense tells us that there will be a gradient developing as the Polar Vortex retreats, the Southeast Ridge amplifies, and a trough swings down into the SW United States. But what is to say that the Polar Vortex can't retreat farther north? What makes you so sure that the warm air advection can't push northward, that the surface low can't strengthen in the Western Arklatex along a frontal zone and then cut inland? There is minimal blocking.

 

I'm not forecasting any specific outcome at this range, just trying to make a point. You can't say anything definitive at this range -- the best idea is to use ensemble guidance and spaghetti plots to try and observe the trends moving forward and get the best idea as to where we're headed. This could still be a blizzard for Chicago or a KU for all of us.

Great post!

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Through 126 hours the Euro has already changed its idea on the baroclinic zone which is not nearly as far south this time when compared to last nights run. With an energetic shortwave about to roar out of the SW US, hard to imagine this being a really cold solution unless we see the PV drop southward.

 

The variance on OP models is fun to watch, but terrible for forecasting. Just noise at this point. Ensembles are much more useful.

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I think, as you said earlier, that a lot depends on where the baroclinic zone ends up after the storm this weekend.

 

The one thing can be deemed as "exciting" is the fact that all of the models are now agreeing on a major precipitation event across much of the Northeast US. But it is simply way too early to begin discussing details. If I was hedging my bets, however, I would argue currently for the bulk of frozen precipitation to be to north and west of the city, potentially in Southern New England.

 

These big energetic shortwave ejecting from the southwest US always give me a pit in my stomach.

 

Yeah, we really need a weak overunning system to make people happy around here.

For now I will probably just follow the ensemble means until we get closer in. 

 

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Yeah, we really need a weak overunning system to make people happy around here.

For now I will probably just look at ensemble means until we get closer in. 

 

I think we can survive with a bigger storm...we just need the PV and confluence to be fairly strong. The low level cold will be impressive as it has been all season.

 

I think this is going to be a major storm system..all guidance is coming into agreement on the shortwave digging really far back into the southwest US and picking up a ton of moisture.

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System crosses into Texas at hour 168. The PV is further north, it's going to cut. Oy vey.

Euro and GFS are working with much of the same numbers on each run cycle. I expected we would see this, not that it's going to happen, but the operational runs of the models will shift back and forth for a while and settle in on an idea come Thursday or Friday.

WX/PT

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