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Pattern Jammin' January

pcbjr said:
e12 or 17 for Larry ... and I'll drive 30 minutes ...
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The member e12 gives SAV 6-7”, which if all snow would be the heaviest in over 180 years. But I assume this counts all wintry as snowfall. So, it could be 0.60-.70” of ZR, 2.5” of sleet, or a mix of these. The 0.60-.70” of ZR would be the heaviest in nearly 100 years and 2.5” of sleet would be the heaviest sleet I’m aware of by a wide margin.
 
deltadog03 said:
Oh btw when (yes I said when) a thread gets started I got dibs. I have a good track record.
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If we have more good runs tonight, then I say we get that thread fired up! All models support a threat at the moment, and ensembles are looking good. Hopefully 00z will continue the good vibes
 
Brick Tamland said:
Well, really with the solution. The ensembles continue to show good snow amounts here, but the ops still seem to be all about potential and not showing any actual snow here yet. Just wondering how they could be so different. We are getting inside a week now, but not really anything showing on the op snow amount maps.
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So we know the ensemble mean is the control run ran 20 more times with slightly different initial conditions and those 20 members (and the control) are then averaged together to give the mean. The control itself is called a control because it controls for deterministic run (OP run) error in initial conditions, and in order to control for this error it must be ran at a lower resolution to create spread (for a lack of a better word)

The thing is, the control has snow. In fact, it has had snowfall for rdu for 4 of the last 5 model runs. The likely reason the Operational itself doesn't is due to the higher resolution and how chaotic the pattern is, but most definitely due to the higher resolution (it essentially chooses one path to go down, the snowless one, and keeps going). Also, usually when the control doesn't have snow, the ensemble members and mean snowfall diminishes. When it has snow, it increases.

The whole idea behind ensemble means is that the ensemble itself has more skill in the LR where the operational doesn't...so this is why most say don't look at the OP...it can sometimes lead you down the wrong path (fools gold in the sense of a super storm on a random run, or it can also lead you to not see the potential in an upcoming pattern). This is why I usually look at ensembles firs thing in the morning and not Op runs.
 
Jon said:
So we know the ensemble mean is the control run ran 20 more times with slightly different initial conditions and those 20 members (and the control) are then averaged together to give the mean. The control itself is called a control because it controls for deterministic run (OP run) error in initial conditions, and in order to control for this error it must be ran at a lower resolution to create spread (for a lack of a better word)

The thing is, the control has snow. In fact, it has had snowfall for rdu for 4 of the last 5 model runs. The likely reason the Operational itself doesn't is due to the higher resolution and how chaotic the pattern is, but most definitely due to the higher resolution (it essentially chooses one path to go down, the snowless one, and keeps going). Also, usually when the control doesn't have snow, the ensemble members and mean snowfall diminishes. When it has snow, it increases.

The whole idea behind ensemble means is that the ensemble itself has more skill in the LR where the operational doesn't...so this is why most say don't look at the OP...it can sometimes lead you down the wrong path (fools gold in the sense of a super storm on a random run, or it can also lead you to not see the potential in an upcoming pattern). This is why I usually look at ensembles firs thing in the morning and not Op runs.
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Thanks. So how far out should we look at the ops and get worried if they still don't show anything versus the ensembles?
 
Yeah, key to getting winter weather here in the carolinas is getting HP to our north/northeast, would not be surprised if that trend continues to see a weak cad signal pop up with a potential storm next weekend and if it already has look for it to get stronger
 
Brick Tamland said:
Thanks. So how far out should we look at the ops and get worried if they still don't show anything versus the ensembles?
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You should only worry if the ensembles start backing off and the op remains snowless. Ensembles backing off would be most 0" members and a few 1-2" members thru 15 days.

For example, 18z GEFS had one 19" member and four 6-9" members. That's not worrisome because it's seeing a potential for a large system. There's no reason to believe what the OP has until the ensemble mean snowfall starts to disappear. I mean, we could be inside day 4, if the ensemble still has snow and Op doesn't, I'm trusting the ensemble.

One of the most important forecasting rules is whether or not the operational agree's with it's ensembles. If the op shows 0F low for RDU but the ensemble mean is 15F, we will likely forecast near 15F. Same goes for snow.
 
Here we go
9d83b857852604372d12b555cc3a278a.jpg


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Whoever sees the storm shown on icon will get high ratio snow. Unfortunately though I bet it drys up as it moves east


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Looks promising ( for now) for the south to get a shot of snow for sure. Would be fun to get some flurries along the gulf coast here...not looking forward to those cold temps the icon is forcasting from the graphic above though. Ugh
 
Storm5 said:
Yuck this ridge out west needs to sharpen up
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lol....

this is why the old GFS sucks...look at how flat that ridge is..no other guidance agrees with what it's doing, yet it keeps doing this. I won't be surprised if it has some kind of clipper to the NE this run. That pattern isn't really fun.
 
Storm5 said:
Yuck this ridge out west needs to sharpen up
4b69e81ea5150cb72b9b0221a45fa121.jpg



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It's trying too on the next couple of frames but probably too little too late.... looking at the ICON has our energy just about coming down the stove pipe, those were the days.
 
Jon said:
BTW this is the same system the FV3 has...too bad it's a 1014mb low, though...still a lot of potential.
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If it amped up though, wouldn't that cause it to cut? Would a -NAO keep the track South even if it were to amp up?
 
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