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Wednesday 12/11 SNE Snow Threat


The 4 Seasons
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37 minutes ago, weatherwiz said:

See...this is where I am a bit weak in analysis. 

Well...I get the southeast shift has little to do with the shallow edge of dry air at 850...

but what about the differences in the s/w relate to a farther southeast shift in precip. This is what I struggle to deal with visually on models. 

I like using the trend gif option on the freely available sites. You can see how the northern stream wave was farther west over the Great Lakes on the NAM runs that had a stripe of heavy snow farther north. This allowed more of the southern stream wave over TX to edge in front of it. The OH Valley vort (now over WI/IA on WV loops) has trended a bit stronger too which flattened the ridge and shoved everything farther S/E. 

 trend-nam-2019121012-f024.500hv.conus.gif.7deef4be7f1fc3e85afa17e7d811144a.gif

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1 hour ago, weatherwiz said:

In a situation like this though, how important is that s/w? Too me, I don't think it is overly important (referring to that OV s/w)...that s/w lags the cold front quite a bit and it's this front (and associated frontal energy) as it pushes through which just yields a different atmospheric state (going from buoyant to subsident). Even if that s/w didn't really get absorbed and maybe the jet feature/speed was more favorable...would it do anything to help? If there was stronger moisture advection which could shoot in with some WAA as we lose the influence of the front...maybe it would be different? 

It's the vast majority of need... 

You have to DIFFFERENTIATE  ... Sorry to yell...just trying to get that point in to people.  If the flow is fast, and a S/W moves into that region ...the net approaches 0... as you do, you get less responses everywhere... until you are at 0, where shit nadda nothing takes place.

Everything in the atmosphere happens because of differential process.  period.  There's nothing else driving this stuff.   

Keep in mind, also, this is the science - how it pertains to this particular set up is a separate discrete analysis.  I'm just pointing this stuff out as possible explanation for the models backing off.  Because from what I am seeing actually depicted from the various sources.. the S/W is getting lost in the flow up there. 

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3 minutes ago, CoastalWx said:

The thing with these setups, and I’m not sure NYC and BOS are out of the loop from this, is that narrow but potent band of snow. There is some really good fronto and lift into the DGZ. Need to watch where That sets up. It may not be far from major cities. 

The though part is that the meteorology rules of thumb are flipped on its head for this event. We typically think in terms of the best snow falling W of forcing, but in this cast it will be E of forcing. I think if you rip and read through the models quickly that's going to bite you on the forecast.

If you generate snowflakes at 700 mb falling at an average 1 m/s they could drift as far as 15 miles E before they reach the ground.

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21 minutes ago, purduewx80 said:

I like using the trend gif option on the freely available sites. You can see how the northern stream wave was farther west over the Great Lakes on the NAM runs that had a stripe of heavy snow farther north. This allowed more of the southern stream wave over TX to edge in front of it. The OH Valley vort (now over WI/IA on WV loops) has trended a bit stronger too which flattened the ridge and shoved everything farther S/E. 

 trend-nam-2019121012-f024.500hv.conus.gif.7deef4be7f1fc3e85afa17e7d811144a.gif

Thank you. I think using gif option's where available will be the best way to go moving forward to really understand things and learn more. This displays it beautifully. 

14 minutes ago, Typhoon Tip said:

It's the vast majority of need... 

You have to DIFFFERENTIATE  ... Sorry to yell...just trying to get that point in to people.  If the flow is fast, and a S/W moves into that region ...the net approaches 0... as you do, you get less responses everywhere... until you are at 0, where shit nadda nothing takes place.

Everything in the atmosphere happens because of differential process.  period.  There's nothing else driving this stuff.   

Keep in mind, also, this is the science - how it pertains to this particular set up is a separate discrete analysis.  I'm just pointing this stuff out as possible explanation for the models backing off.  Because from what I am seeing actually depicted from the various sources.. the S/W is getting lost in the flow up there. 

Gotcha...this helps. Great explanation. 

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1 minute ago, Spanks45 said:

It seems like the only surprise at this point is going to be that we actually get more than just a slushy inch or 2 on grassy surfaces. Seems like maybe a small area might see 2-3 inches, probably eastern areas....Some lucky person might measure 4 inches on their deck

Let’s grab an inch and focus our tracking to the D7 threat.

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20 minutes ago, OceanStWx said:

The though part is that the meteorology rules of thumb are flipped on its head for this event. We typically think in terms of the best snow falling W of forcing, but in this cast it will be E of forcing. I think if you rip and read through the models quickly that's going to bite you on the forecast.

If you generate snowflakes at 700 mb falling at an average 1 m/s they could drift as far as 15 miles E before they reach the ground.

Yep, funny because I was thinking that earlier. Although, looks like NW flow relaxes a bit towards 12z. But yeah this isn’t exactly flow going in the direction of best snows falling just on the colder side of said fronto. That said, feel like this will have a sneaky band somewhere unless it completely moves east. 

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18 minutes ago, Baroclinic Zone said:

12z RGEM is still bullish over S/SNE

It’s been ticking SE but it’s now in its range and it’s NW of the Euro and NAM.  The RGEM runs sort of like an MLB team’s bullpen.  It’s either hot or cold winter by winter and it takes you 2-3 storms to see its tendency.  It has performed well so far IMO going back to mid November though it had a few localized busts on the storm last week.  It was 100% useless last winter 

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3 minutes ago, CoastalWx said:

Yep, funny because I was thinking that earlier. Although, looks like NW flow relaxes a bit towards 12z. But yeah this isn’t exactly flow going in the direction of best snows falling just on the colder side of said fronto. That said, feel like this will have a sneaky band somewhere unless it completely moves east. 

Even the crappy solutions show pretty intense f-gen in the mid levels, it's just narrow. Could be a classic couple of inches for E MA while Dave is staring up at starlight filtering through the cirrus.

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On 12/9/2019 at 9:36 AM, dryslot said:

Wouldn't shock me though if he would end up with the most snow from this, Eastern areas look to be favored while there is still moisture left, Comes down to timing though getting the colder air in while its still overhead.

That area is what i would favor.

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4 minutes ago, OceanStWx said:

Even the crappy solutions show pretty intense f-gen in the mid levels, it's just narrow. Could be a classic couple of inches for E MA while Dave is staring up at starlight filtering through the cirrus.

This is some of the strongest fronto I think I've seen on a forecast model:

image.png.4be3fc4ad31253a948e51498cb42eb44.png

If you analyze further you can easily see as well why the best chance for snow would be on the east side as opposed to the west side.

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22 minutes ago, weatherwiz said:

This is some of the strongest fronto I think I've seen on a forecast model:

If you analyze further you can easily see as well why the best chance for snow would be on the east side as opposed to the west side.

The tough part is that 850 mb f-gen is well east of the 700 mb forcing.

i.e. way too sloped to really help enhance omega for warning criteria amounts.

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Just now, OceanStWx said:

The tough part is that 850 mb f-gen is well east of the 700 mb forcing.

i.e. way too sloped to really help enhance omega for warning criteria amounts.

yeah that's a huge issue here too. 

It does seem though that they sort of become more stacked moving through the morning across RI/SE MA...this is virtually where any hope exists for accumulating snow. 

Hell at this juncture there's a chance someone in W CT doesn't even see a flake. Precip is going to shit down quickly. 

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17 minutes ago, weatherwiz said:

yeah that's a huge issue here too. 

It does seem though that they sort of become more stacked moving through the morning across RI/SE MA...this is virtually where any hope exists for accumulating snow. 

Hell at this juncture there's a chance someone in W CT doesn't even see a flake. Precip is going to shit down quickly. 

I hate when it does that. I like the slow methodical visits to the crapper where a man has time to think and look at his phone peacefully.

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