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March 6-8th Ocean Storm Discussion Part III


Baroclinic Zone

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Thanks for the excellent explanation. 

 

In a nutshell, if the NAM has the synoptics right it'll score a coup, but if we look at synoptic verification scores for GFS vs NAM past 48 hrs or better Euro vs NAM, this is a no brainer on which model camp will probably be more right come verification time.

 

Well it shows us what our various scenarios are for this storm. The NAM represents a plausible outcome. But signs point towards the interaction with that shortwave over the Lakes being the critical player. The NAM misses the phase, the Euro is later, the GFS aggressively drives it SE and phases earlier.

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How are you feeling for our area?  lots of QPF potentially, temps are a worry for me.

 

I'm playing it conservative right now.  QPF will not be an issue in my mind.  Euro/SREFs are just a plastering.  Surface temps will be in the 30s so we'll need dynamics to keep us all snow.

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Verified here within a 1/4" on the blizzard

They can be weenieish. Some of the members gave you and I 50-70" for the blizz. I think inside 24hrs the mean isn't too bad. There's decent SREF spread still though, so I'd personally be hesitant in putting faith in them.
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I think it helps to view it in a potential vorticity model. The phasing makes a little more sense than looking at individual vorticity maxima at H5. The NAM advects the potential vorticity on the tropopause eastward, resulting in a missed phases. It tries at 12z, but just misses the connection. The GFS on the other hand (06z) advects this PV anomaly in the northern stream south and east, which interacts with the southern stream PV anomaly by tugging it northward. The two stream phase completely later on, which is when we get the stall and loop S of the benchmark.

 

I think the warmth aloft comes from the missed phase. The NAM is dynamically as intense as the GFS, so heights remain high to the north rather than tighten towards the center as the GFS depicts. The GFS does draw down that northern stream cold pool, while the NAM lingers it over the Lakes.

 

Yeah thanks.  I know what I'm looking at but wanted to make sure what I thought was happening was happening.  The NAM came steadily towards the Euro, if you overlay the 0z/6z/12z NAM runs and then look at the 12z NAM vs the 0z Euro...we can see it's coming back to the fold.   That will be the feature to watch with the rest of the models right now.  RGEM/GGEM last night were also slow in diving that feature down which probably explains their less intense solutions.

 

The 12z RGEM appears to have come more towards the NAM solution in a delayed phase.   It's possible the NAM is scoring a coup here, but we'll see.

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Do you guys agree?

 

Todd Gutner‏@ToddWBZ

With a NE wind off H2O, surface will be too warm for first half of storm for much if any snow accum outside of hills...IMO...

 

Lol. It's pretty obvious I do since I responded to him and agreed.  

 

My thoughts right now are lots of rain inside 495 turning into maybe a little slop.  Outside 495 a few inches of crap. And then possibly a max of 10" in Worcester County.

 

I'm just worried that the precip rates necessary for snow never really make it. 

 

Well worried about a lot actually.

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Yeah thanks.  I know what I'm looking at but wanted to make sure what I thought was happening was happening.  The NAM came steadily towards the Euro, if you overlay the 0z/6z/12z NAM runs and then look at the 12z NAM vs the 0z Euro...we can see it's coming back to the fold.   That will be the feature to watch with the rest of the models right now.  RGEM/GGEM last night were also slow in diving that feature down which probably explains their less intense solutions.

 

The 12z RGEM appears to have come more towards the NAM solution in a delayed phase.   It's possible the NAM is scoring a coup here, but we'll see.

 

 

RGEM would be a pretty pedestrian solution, maybe low end warning at most in the hills...advisory snow elsewhere, perhaps a bit higher interior SE MA. Conservative wins if RGEM is correct.

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Yeah thanks.  I know what I'm looking at but wanted to make sure what I thought was happening was happening.  The NAM came steadily towards the Euro, if you overlay the 0z/6z/12z NAM runs and then look at the 12z NAM vs the 0z Euro...we can see it's coming back to the fold.   That will be the feature to watch with the rest of the models right now.  RGEM/GGEM last night were also slow in diving that feature down which probably explains their less intense solutions.

 

The 12z RGEM appears to have come more towards the NAM solution in a delayed phase.   It's possible the NAM is scoring a coup here, but we'll see.

 

By 48 the RGEM is dumping the energy, FTMP into the trough.  NAM is on its own.  Still, we toss.

 

Notice the difference between the 0z GGEM and the 12z RGEM to illustrate the point.  The 12z RGEM came back towards a slightly more aggressive phase, we see the offshore low has it's closed contour up over us, versus just offshore.  The RGEM is colder this run through the layers (at least the ones I can see)

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RGEM would be a pretty pedestrian solution, maybe low end warning at most in the hills...advisory snow elsewhere, perhaps a bit higher interior SE MA. Conservative wins if RGEM is correct.

 

Check out the lakes, it's split somewhere between the NAM and Euro.  More phasing than the NAM, but not as much as the Euro. 

 

Could be a harbinger here of later shifts.  I do think the RGEM is wrapping up pretty good at 48 too though.

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I'm playing it conservative right now.  QPF will not be an issue in my mind.  Euro/SREFs are just a plastering.  Surface temps will be in the 30s so we'll need dynamics to keep us all snow.

 

definitely gonna need some help with the temps. would be a meh end to the year if its mostly a cold rain or a non accum snow.

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Check out the lakes, it's split somewhere between the NAM and Euro.  More phasing than the NAM, but not as much as the Euro. 

 

Could be a harbinger here of later shifts.  I do think the RGEM is wrapping up pretty good at 48 too though.

Looks real good on the REG PCPN site
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GFS and NAM are worlds apart in how they handle that energy by even 30 hours.  GFS digging down, NAM got stopped by customs at the border and is trying to find an entry point further east.

 

The GFS is off of its earlier solutions though, there is definitely a more easterly component to that energy. 

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They can be weenieish. Some of the members gave you and I 50-70" for the blizz. I think inside 24hrs the mean isn't too bad. There's decent SREF spread still though, so I'd personally be hesitant in putting faith in them.

 

Yeah, But the mean stayed pretty steady, There were a few weenie members well north of there on several runs but in the end like you said, It did ok, I just use it more as a reference and just another piece of guidance, I think you and i will be on the sidelines for this one

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