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February 5th beefed up swfe thread-let's get some December 2007 juju,

weathafella

By weathafella,
in New England

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free_man

free_man

Posted
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Small world lol. Yeah I'm thinking 2-4 is a good call, however trends show we might be in for a bit more. 6-10, even if modeled right now, still seems like a longshot in this setup for this area

I'd take 4-7" with sleet/zr and dryslot and run.  Not sure I would forecast that, though.  Fragile area for hanging onto cold.  :D

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free_man

free_man

Posted
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That would be great, and we could lock it in. It is tough, but this isn't the worst location to be honest.

Your area obviously has a shot at close to a foot

I only hope NNE gets hit.  Either way we'll probably get 4-6" here over to N ORH. The trend is NOT good for NNE and no one can deny that, Northern ME may not see a flake.

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ORH_wxman

ORH_wxman

Posted
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The SWFE term was invented by Will and Ekster. I will defer to them.

 

 

There is no real special "law" to them...its not peer reviewed science. :lol:

 

 

But we always referred to the storms with screaming SW flow from H5 to H7...sometimes the lower mid-levels would try and back a bit toward the E like 850mb...and the surface winds were very frequently north or northeast since the sfc refleciton almost always got squeezed underneath SNE in all of these.

 

Anyone can look at any of the SWFEs from 12/13/07, 12/16/07, 12/19/08, 2/22/08, 1/7/09, 1/11/09, 1/28/09, etc...every single one has ripping SW flow in the H5-H7 layer and all have a sfc reflection going out south of SNE or over SE SNE. Some are a bit colder than others and some have a bit more redevelopment at H85 than others, but the common denominator is that H5-H7 layer and cold  surface.

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HoarfrostHubb

HoarfrostHubb

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There is no real special "law" to them...its not peer reviewed science. :lol:

But we always referred to the storms with screaming SW flow from H5 to H7...sometimes the lower mid-levels would try and back a bit toward the E like 850mb...and the surface winds were very frequently north or northeast since the sfc refleciton almost always got squeezed underneath SNE in all of these.

Anyone can look at any of the SWFEs from 12/13/07, 12/16/07, 12/19/08, 2/22/08, 1/7/09, 1/11/09, 1/28/09, etc...every single one has ripping SW flow in the H5-H7 layer and all have a sfc reflection going out south of SNE or over SE SNE. Some are a bit colder than others and some have a bit more redevelopment at H85 than others, but the common denominator is that H5-H7 layer and cold surface.

When did you and Mike first start to classify them etc. was it during Eastetn?
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Baroclinic Zone

Baroclinic Zone

Posted
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That would be great, and we could lock it in. It is tough, but this isn't the worst location to be honest.

Your area obviously has a shot at close to a foot

The 12z Euro run today is what we would want for this area in SEMA.  Just keep an eye on the confluence to the N.  See my enclosed image.  Notice how the flow is compressed over the northeast.  The other thing to look for is the strength of the s/w coming out of the southwest.  There does not look to be discernible differences between the strength of the 00z and 12z runs of the Euro so most of the trend we are seeing leads me to think that it is driven by the confluence to the N.

 

As of right now I would definitely have snow in the forecast withe the potential for a few inches.  The Euro would be likely an all frozen system with on the order of 8-10".

 

The kicker in all this is that there seems to always be a north kick to these systems in the day prior to it so something to keep in mind. 

 

post-238-0-48583300-1391299105_thumb.gif

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CoastalWx

CoastalWx

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The trend north shouldn't be confused with the recent trends in storms as of late. There is a reason why these can come in further north than modeled 72 hrs out. One rule to always keep in mind is that storms that are of gulf origins or even ones that just tap into that warm humid air seem to tick north due to all the convection and release of latent heat. This latent heat is warmer air in the mid levels that gets advected downstream and pumps up the ridge a bit. An enhanced downstream ridge means the low rides further NW. It's not always the primary reason....but this storm looks like it could be a classic example of the GOM doing its dirty work. We will see.

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TauntonBlizzard2013

TauntonBlizzard2013

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The 12z Euro run today is what we would want for this area in SEMA. Just keep an eye on the confluence to the N. See my enclosed image. Notice how the flow is compressed over the northeast. The other thing to look for is the strength of the s/w coming out of the southwest. There does not look to be discernible differences between the strength of the 00z and 12z runs of the Euro so most of the trend we are seeing leads me to think that it is driven by the confluence to the N.

As of right now I would definitely have snow in the forecast withe the potential for a few inches. The Euro would be likely an all frozen system with on the order of 8-10".

The kicker in all this is that there seems to always be a north kick to these systems in the day prior to it so something to keep in mind.

f96.gif

Cool thanks for the explanation. That confluence will be key over the next couple days. And yeah when we are on the line here, those northwest ticks could do us in

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weathafella

weathafella

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The reason for the trend to go under us is the confluence strengthens as the system tries to cut, You can clearly see it shunting east just when you think it's going further north. Looping the pv spoke one sees how it slaps things east. So I think the lesson here is that confluence probably will be stronger than initially progged but today was IMHO a big over correction. I think a 25 mile trend north is all I could take imby...maybe 50 miles for the front ender.

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CoastalWx

CoastalWx

Posted
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Does the Monday system coming farther north now have any bearing on what this one does or no?

 

I've been trying to wrap my head around that.  I think the reason why the models are ticking SE for Wednesday has to do with what is going on well north of us. A PV lobe is swinging around SE Canada and that is helping to cause the big S/W down south to hit a meat grinder. I don't like seeing such a disjointed system, but that's what is modeled.  Usually these disjointed systems are just one big WAA dump while further north sees lingering deformation snows.

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OceanStWx

OceanStWx

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I've been trying to wrap my head around that.  I think the reason why the models are ticking SE for Wednesday has to do with what is going on well north of us. A PV lobe is swinging around SE Canada and that is helping to cause the big S/W down south to hit a meat grinder. I don't like seeing such a disjointed system, but that's what is modeled.  Usually these disjointed systems are just one big WAA dump while further north sees lingering deformation snows.

 

Whether you choose to look at potential vorticity or your standard 500 mb vorticity, you can see that as the s/w ejects from the Tennessee Valley it just gets sheared out. And there is no difference there between the Euro and GFS.

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CoastalWx

CoastalWx

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Whether you choose to look at potential vorticity or your standard 500 mb vorticity, you can see that as the s/w ejects from the Tennessee Valley it just gets sheared out. And there is no difference there between the Euro and GFS.

 

Whether you choose to look at potential vorticity or your standard 500 mb vorticity, you can see that as the s/w ejects from the Tennessee Valley it just gets sheared out. And there is no difference there between the Euro and GFS.

 

Yep. I know Powderfreak is currently having a candlelight vigil with the rest of the reindeer sweater posse, but if it weren't for that confluence..this thing would mix to Montreal.

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Baroclinic Zone

Baroclinic Zone

Posted
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The reason for the trend to go under us is the confluence strengthens as the system tries to cut, You can clearly see it shunting east just when you think it's going further north. Looping the pv spoke one sees how it slaps things east. So I think the lesson here is that confluence probably will be stronger than initially progged but today was IMHO a big over correction. I think a 25 mile trend north is all I could take imby...maybe 50 miles for the front ender.

 

 

Caution flags?

 

 

For what?

 

Caution flags would be for the confluence to lift N & E out of where it is currently modeled.  You know what would happen there.  The other caution flag is exactly what Scott posted about systems coming out of the southwest with the latent heat release pumping up the ridging ahead of the system.  I think you can figure out what that would mean.

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CoastalWx

CoastalWx

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Posted

Certainly for a mature cyclone around the benchmark.

 

Given the look aloft right now, people just need to realize there is a limit to this system. We won't see forecast snowfall amounts continue to increase right through the onset.

 

Yeah there are a few of them....I just didn't know what he was thinking of.

 

Put me in the camp of this ticking north from the 12z euro track. Although lately things have trended north when I thought otherwise so who knows. :lol:

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HoarfrostHubb

HoarfrostHubb

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Caution flags would be for the confluence to lift N & E out of where it is currently modeled. You know what would happen there. The other caution flag is exactly what Scott posted about systems coming out of the southwest with the latent heat release pumping up the ridging ahead of the system. I think you can figure out what that would mean.

I figured it was about the condition of the s/w
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Baroclinic Zone

Baroclinic Zone

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I figured it was about the condition of the s/w

Right now I have not seen much difference between 00z and 12z today with the s/w coming out of the southwest so that would lead me to believe all the model shifts S have been a result of the confluence to the N.  Is it correct, we don't know.  This is why/when we should lean on the ensembles and climo.

 

Where I see it, there is just no reason to side with one solution.  We know there will be a really juiced system coming into the area midweek.  We know it's going to snow.  The antecedent airmass looks good for that.  We just don't know for how long if at all.  That would lead into precip types and duration of them as the ML's would warm above 0c.  Sleet/Freezing Rain/Rain.  Just discuss all the possibilities.

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