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The March 6 Storm- The (last) Great White Hope


stormtracker

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That's a weird looking progression for the low.

 

The GFS has that little dipsy-doo in it too.  Just not as noticeable to us because the track first brings the low further north and the dip happens further east.  If you want to see it, click "Loop All."

 

http://mag.ncep.noaa.gov/list_files_area.php?model=gfs&cycle=12&area=atlantic&param=precip_p03

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It looks like the Euro is vertically stacked/occluded about 6-hours earlier than the GGEM or GFS. I'm guessing that it then either pops off another low right where we have the best regional baroclinic gradient...either that or some embedded meso low pressure begins to take over as the now occluded original low starts to fill. I'm sure I have the dynamics of the situation wrong but the low is clearly occluding earlier on the Euro than it is on the other globals. Is it correct? Heck if I know, you can probably make an argument for and against its accuracy just based on the virtues of its resolution (relative to the other models) alone. It's a tough nuance to get worked up about from 78 hours out...  

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Really interesting difference between the GFS and Euro with regards to how they treat the 500 and surface lows.  The GFS doesn't stack until it is off the coast, that helps us by providing a negative-tilt trough like aspect, stalling the surface low.  The Euro stacks over land in NC, and then dives SE, an evolution that I am not used to seeing.

Yeah, like he said. 

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Really interesting difference between the GFS and Euro with regards to how they treat the 500 and surface lows.  The GFS doesn't stack until it is off the coast, that helps us by providing a negative-tilt trough like aspect, stalling the surface low.  The Euro stacks over land in NC, and then dives SE, an evolution that I am not used to seeing.

Yeah the EC was doing that a few runs back as well. I think it had the track from Elizabeth City southeast to south of Cape Hatteras. You rarely if ever see that happen around that longitudinal benchmark. For some reason...that particular solution is the one that ends up being the operational run. Meanwhile, the EC mean of all 50 members never had that funky SE shift as the surface low moved offshore.

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Really interesting difference between the GFS and Euro with regards to how they treat the 500 and surface lows.  The GFS doesn't stack until it is off the coast, that helps us by providing a negative-tilt trough like aspect, stalling the surface low.  The Euro stacks over land in NC, and then dives SE, an evolution that I am not used to seeing.

 

 

It looks like the Euro is vertically stacked/occluded about 6-hours earlier than the GGEM or GFS. I'm guessing that it then either pops off another low right where we have the best regional baroclinic gradient...either that or some embedded meso low pressure begins to take over as the now occluded original low starts to fill. I'm sure I have the dynamics of the situation wrong but the low is clearly occluding earlier on the Euro than it is on the other globals. Is it correct? Heck if I know, you can probably make an argument for and against its accuracy just based on the virtues of its resolution (relative to the other models) alone. It's a tough nuance to get worked up about from 78 hours out...  

 

 

Yeah the EC was doing that a few runs back as well. I think it had the track from Elizabeth City southeast to south of Cape Hatteras. You rarely if ever see that happen around that longitudinal benchmark. For some reason...that particular solution is the one that ends up being the operational run. Meanwhile, the EC mean of all 50 members never had that funky SE shift as the surface low moved offshore.

 

Good, I'm glad I'm not the only one who perhaps questions it.

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No one has mentioned yet the glaring differences with the Canadian-NW Atlantic setup. The ECMWF is trying to incorporate another northern wave, which is what the actual storm originally splits from. It has no interaction with the NW Atlantic low either.

The GFS does NOT incorporate this Canadian Wave and interacts with the NW Atlantic Low.

So, to simply say that the ECMWF has more blocking is actually false. The ECMWF actually lifts the NW Atlantic Low out faster. This is what I meant last week in the Philly Subforum when I said "the northern stream is littered with waves." A lot of players.

If the influence of this continues to get incorporated, I could actually see a SE trend in the next 48 hrs.

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Good, I'm glad I'm not the only one who perhaps questions it.

I brought up the occluding/redeveloping process last night as a possible issue but there are still large-scale type of differences going on in the Canada-NW Atlantic sector.

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Good, I'm glad I'm not the only one who perhaps questions it.

I  don't see how the EURO solution can be correct for the simple fact that

the 300 mb pattern is generally aligned from SW to NE.  The EURO

would assume that the 500 mb low would have enough vorticity to either

buckle the flow at 300 mb or simple ramrod across.   The EURO solution reminds

me of tropical models that use persistence only.

 

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No one has mentioned yet the glaring differences with the Canadian-NW Atlantic setup. The ECMWF is trying to incorporate another northern wave, which is what the actual storm originally splits from. It has no interaction with the NW Atlantic low either.

The GFS does NOT incorporate this Canadian Wave and interacts with the NW Atlantic Low.

So, to simply say that the ECMWF has more blocking is actually false. The ECMWF actually lifts the NW Atlantic Low out faster. This is what I meant last week in the Philly Subforum when I said "the northern stream is littered with waves." A lot of players.

If the influence of this continues to get incorporated, I could actually see a SE trend in the next 48 hrs.

 

I just saw this, and wow, that is a huge difference. The GFS has trended away from interaction with the Canada shortwave (probably why it brings the precip a bit north this run). Why is this interaction causing a shunt? Is it due to the orrientation. Normally, I see shortwave interaction causing a phase, and dragging the storm further north. Is the angling just wrong?

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I  don't see how the EURO solution can be correct for the simple fact that

the 300 mb pattern is generally aligned from SW to NE.  The EURO

would assume that the 500 mb low would have enough vorticity to either

buckle the flow at 300 mb or simple ramrod across.   The EURO solution reminds

me of tropical models that use persistence only.

These processes are dynamical, i.e. over time. The problem is you have yet another northern stream s/w on the ECMWF showing up (what the storm originally splits from and no this isn't the solution from last week where phasing was trying to happen). As this begins to dive SE underneath the block, which the GFS does not do, it adds forward momentum to the southern wave...pushing it SE under the blocking even more.

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I  don't see how the EURO solution can be correct for the simple fact that

the 300 mb pattern is generally aligned from SW to NE.  The EURO

would assume that the 500 mb low would have enough vorticity to either

buckle the flow at 300 mb or simple ramrod across.   The EURO solution reminds

me of tropical models that use persistence only.

 

attachicon.gifgfs_namer_069_300_wnd_ht.gif

 

how can you use the GFS's 300 mb pattern to make an interpretation of the Euro?

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No one has mentioned yet the glaring differences with the Canadian-NW Atlantic setup. The ECMWF is trying to incorporate another northern wave, which is what the actual storm originally splits from. It has no interaction with the NW Atlantic low either.

The GFS does NOT incorporate this Canadian Wave and interacts with the NW Atlantic Low.

So, to simply say that the ECMWF has more blocking is actually false. The ECMWF actually lifts the NW Atlantic Low out faster. This is what I meant last week in the Philly Subforum when I said "the northern stream is littered with waves." A lot of players.

If the influence of this continues to get incorporated, I could actually see a SE trend in the next 48 hrs.

The Intermountain ridge over the Rockies is much more organized at 300 mg on the GFS, with the Euro the ridge is more sloppy and sprawling.

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These processes are dynamical, i.e. over time. The problem is you have yet another northern stream s/w on the ECMWF showing up (what the storm originally splits from and no this isn't the solution from last week where phasing was trying to happen). As this begins to dive SE underneath the block, which the GFS does not do, it adds forward momentum to the southern wave...pushing it SE under the blocking even more.

Well, this is the sort of unbiased analysis we need.  HM, I think you are discussing an elongated vorticity complex that is vertically oriented just a bit north of the Great Lakes.  It appears muted and weak on the GFS and much more intense on the EURO. 

 

How soon will we know which is correct?

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HPC Prob snow graphics are pretty gung-ho for our area in their afternoon update

...and as they should be. Keep in mind the autoensemble probs that come out first are not the final 10/40/70 probs of at least 4/8/12" of snow, and are 3/4 weighted toward the SREF (ensemble of 21 SREF members and 7 operational runs). Bottom line is these are very SREF-heavy.

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