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Feb 8th-9th Do We Finally Get A Coastal?


dryslot

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Toggling those frames like that ... the differences appear entirely related to resolution - the GFS is clearly "blurrier", where the ECM has all kind of discrete features available to interact in, and among the various streams. 

 

This may be a complete lie ... but I thought the GFS's grid was actually more coarse out in time, and that it computes at a higher resolution crossing from middle range into nearer terms.  If there is any truth to that, "perhaps" the stream interaction is merely that finer mesh bringing the event into focus.  

 

But that could be science fiction if the prior statement isn't true. 

 

Either way, that aside ... This thing - as is - has a big time convective aspect upon that 84-hour chart.  You can see that in the QPF, but as suggested by the jet coupling going on at that time between the southern stream system that is curling cyclonically into the eastern/front side of the N stream trough.  That jet max intermingling is going to have a zone of exotic UVM and if that sucker bumped just 50 mile NW there would be a lot of lightning and thunder falling amid some obscenely tall snow fall rate.  

 

Yes the ECMWF has higher resolution, but that doesn't take away the fact that is also has more Atlantic ridging than the GFS has (at least yesterday's 00z runs did, when the GFS and ECMWF had the largest disparity). My point that I was highlighting is that you need the southern stream shortwave to be amplified enough to generate the convection you need for the non-linear diabatic process to be initiated. The GFS was not allowing that yesterday, but today it has come on board, partly due to the subtle but noticeable ridging starting to appear over the Atlantic. 

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You aren't saying that because it puts you on the jackpot are you? Of course not!

That thought occurred to me....but with other models coming on board and now seeing amped up solutions...and given that the shortwaves just started getting sampled well, I think it could amp more.  But you know what I mean?  984 near CC wouldn't necessarily to be bad for you with that High.

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Actually, Ryan, it's usually the southern stream that induces the northern stream (subsume).   What happens is the N stream will move along a given latitude, but when a southern stream times right, the geopotential height resistance is lowered to the S of the N stream and that causes a latitudinal decent - the southern stream then cyclonically curls N around the stress in the flow, and that is the initiation of phasing.  

 

Dr. Frank Colby did an interesting paper on Feb 1978 that really shows how this takes place.  Post reading that analysis I have gone back over many double streamer unions and they were almost all the same way, for full or quasi phase.   

 

What would be a really interesting experiment would be to take a verified subsume result, and preprogram the input grid to remove the southern stream - the N stream would not descend in latitude in the absence of the southern stream timing, if theory is correct.   But - and this is going to sound inCREdibly nerdy, but I have watched vortexes in simmering pots of water, where a rotating eddy suddenly slips toward a passing stream velocity.  It makes perfect sense to me, and although I am the biggest dork on the "phase" of the planet, there is something to be said for microscale modeling because that is what experimental lab work uses.  

 

John

Interesting John but I don't think this is always the case.

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Yes the ECMWF has higher resolution, but that doesn't take away the fact that is also has more Atlantic ridging than the GFS has (at least yesterday's 00z runs did, when the GFS and ECMWF had the largest disparity). My point that I was highlighting is that you need the southern stream shortwave to be amplified enough to generate the convection you need for the non-linear diabatic process to be initiated. The GFS was not allowing that yesterday, but today it has come on board, partly due to the subtle but noticeable ridging starting to appear over the Atlantic. 

 

 

It's interesting ... could also be a chicken/egg thing ...  I mean, the GFS may not have had as much lead ridging over the Atl, because it was not seeing/detecting the southern stream presence, yesterday.  Now that it is, it rolls a bit more out ahead and there we go - Fascinating.  

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Kudos to those who saw this potential... I was skeptical given the fast h5 flow as depicted earlier this week, but as TT said, the gradient slackens by Fri-Sat.

 

SNE sitting in the sweet spot 84 hours out...

We can all read model solutions, but at this point, what are the more likely flags at this point: a more coastal-hugging track, or a more progressive OTS solution?

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gfs ens mean is about exactly where you'd expect it to be. 

 

 

This is more of holistic statement ... but thinking back along the years, you really want this thing right where it is for this time lead.  If this were buggers perfect at 84-96 hours out, particularly in this seasons penchants for poor performance by the models, you'd be inclined to wonder what will inevitably go wrong.

 

Probably still can do a good bit of that pessimism, but again ... there is wiggle room in the positive direction, whereas if this were perfect at this time range - your're talking about 4 days of having to maintain a perfect system.  THAT almost never happens on planet Earth. 

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Kudos to those who saw this potential... I was skeptical given the fast h5 flow as depicted earlier this week, but as TT said, the gradient slackens by Fri-Sat.

 

SNE sitting in the sweet spot 84 hours out...

We can all read model solutions, but at this point, what are the more likely flags at this point: a more coastal-hugging track, or a more progressive OTS solution?

I'm not expert, but from what I've been reading OTS due to the progressive flow, I'm sure I will be corrected. :)
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The QPF is going to be there it seems for at least a low end warning event, its just a question of whether we can wrap up a big phased bomb which helps out the coastline areas in E and SE areas...if you leave the two streams a bit more seperate, then ptype issues creep in..esp in southern spots.

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CMC drives warmth into nh with a strengthening hp to the north. Doubt that.

 

 

That's a bias of the GGEM actually ... meridional warming.  It loves to punch warm sectors into spring maritime patterns too, when/where we all know what BDs will do to that sort of vision.  

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