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Plains Weather Discussion


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GFS ejects the lead wave about 100 miles farther N than the ECMWF, but overall they have a very similar look aloft. But that 100 miles makes a huge difference in terms of growth potential as well as GOM feed. To have an epic superstorm aka ECMWF that upper low needs to eject farther S and deepen faster. Even in GFS form an awesome winter storm.

Note the wave ejecting latitude difference between GFS/ECMWF. That said, beginning to get excited on our first legit CO Low in over a year.

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The 18z GFS drops a pretty impressive upper system into the plains by D7

500mb winds crank up to near 120+ knots...

Dr. Greg Forbes

SUN APR 1

Monitor subsequent forecasts, as this could turn into a severe outbreak from

MN to central TX. The GFS and ECMWF models disagree enough on the upper-air

ingredients that it's too early to pinpoint the exact severe area.

grearth2012-03-2622-04-49-50.png

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CMC is trending more towards the GFS with its most recent run...note the plethora of potent shortwaves looking to rotate around this trough:

The 18z GFS drops a pretty impressive upper system into the plains by D7

500mb winds crank up to near 120+ knots...

Perhaps not the best forecasting...but I am not even getting remotely excited until the ECMWF suggest anything like the GFS/CMC. The EC/ECENS delay any potential trough by an entire 2-3 days.

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Perhaps not the best forecasting...but I am not even getting remotely excited until the ECMWF suggest anything like the GFS/CMC. The EC/ECENS delay any potential trough by an entire 2-3 days.

I agree, but with a setup like this off the West Coast and out east prior to the trough forming (nicely deamplified ridge, rather zonal flow pattern, with that lead anomaly flattening the ridge even further), I'd have to think digging of the incoming upper/mid level jet streak would be a more likely scenario than what the Euro is showing after this right now, I mean there is a ton of UL energy associated with this feature:

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I agree, but with a setup like this off the West Coast and out east prior to the trough forming (nicely deamplified ridge, rather zonal flow pattern, with that lead anomaly flattening the ridge even further), I'd have to think digging of the incoming upper/mid level jet streak would be a more likely scenario than what the Euro is showing after this right now, I mean there is a ton of UL energy associated with this feature:

The EC/GFS handle the Pacific in vastly different ways. GFS goes amplification crazy cross the Pacific while the EC has a huge broad trough/vortex across the GOA. For now will stick with an EC solution and its handling of the Pacific pattern.

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I kind of meant more on the smaller scale with the feature off the coast of the Pacific NW and Northern California, which the 12z Euro and 12z GFS actually handle rather similarly at the 96-120 hr period.

Right, I know exactly what you are talking about, but downstream amplification across the CONUS with that day 5 wave will be highly dependent upon the upstream development of a potential height anomaly across the Pacific. GFS really amplifies the entire flow pattern day 5-6.

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Ah ok now I see what you're getting at, GFS does amplify the ridge which allows the trough to dig further than the Euro. One thing I will mention, the GFS nailed the amplification (and was quite consistent with its verbatim from quite far out) leading to the big meridional trough/cut off last week, which is why I might be giving it the edge right now.

The CMC is essentially a compromise between the two verbatims (although perhaps leaned slightly in favor of the GFS) and actually may paint the most potentially volatile setup, tbh.

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The CMC "caved" to the EC in that the day 5 wave is lower amplitude and much weaker than progged in the 12Z and current GFS. Much of the energy remains across the GOA as a broad upper low/vortex. Possibly something to watch farther out...still interested to see the 0Z EC, but my guess is it prolly does not change much...certaintly won't be progging anything as dramatic as the GFS op runs the last couple days.

CMC day6:

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12z GFS continues to go gung ho on development of a bombing low in the plains. Don't know how realistic this is given the Euro's initial hesitancy.

Backs off some on instability, at least for the northern plains, the wave does not dig as deep (like the Euro, imagine that), backed off on upper air wind fields as well, and there is low pressure farting around in Texas inhibiting moisture return. Hard to imagine there will be an elongated 980ish mb low in the plains and not decent convection somewhere though...

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That stupid @#^%#& upper low that dinks around in the Arklatex on most model solutions late this week into Saturday could very well be the undoing of this setup, at least in terms of high-end potential. There's a fairly stark difference between the 00z and 12z GFS moisture fields, and although the 12z does have low-level moisture recovering just in time for OK on Sunday afternoon, the trend is not good.

Since this (potential) trough is far lower-amplitude than the March 18-19 event, I'd like to see top-shelf moisture quality in order to get excited, given capping issues and less-impressive kinematics. The ceiling of potential for Sunday remains high, but the probability of realizing something significant strikes me as rather low, for now.

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Backs off some on instability, at least for the northern plains, the wave does not dig as deep (like the Euro, imagine that), backed off on upper air wind fields as well, and there is low pressure farting around in Texas inhibiting moisture return. Hard to imagine there will be an elongated 980ish mb low in the plains and not decent convection somewhere though...

Keep in mind this can be a good thing in terms of discrete supercells, if you get too deep and sharp of an upper trough, the shear profiles will become linear-favoring.

Forbes and the SPC have actually dropped some significant wording WRT this system despite the model differences, which is interesting.

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00z GFS really doesn't have much in the way of that pesky upper low that Brett mentioned. That said, the main threat may be shifting away from the Plains eastward on Sunday. And boy is that a large extent of 60s dews...wow. Sub 982 mb bomb in MN and sub 1000 mb heights extending way far south (actually looks like it may be popping a secondary SLP in the TX/OK panhandles)...

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Both GFS and Euro maps by day 10 look totally Nino to me. This trough coming thru is a big chunk of that semi-permanent (or so it seemed for the last 2 years) Gulf of Alaska low. I see ridging showing up over the GOA and troughing in the east on the extended now... might explain why the models are having such an awful time of things lately. Just an observation is all...

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