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Western Pa / Pittsburgh area Winter Discussion ❄️☃️


north pgh
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So I was checking out the 3K NAM at 6Z which is a pretty decent hit (visualized) for PIT.  We wet bulb around 1 PM tomorrow and have decent lift in the DGZ for the first few hours.  Then we wax and wane, transitioning to a loss of consistent lift there.  Until ~05Z (which would be around midnight) when we hit maximum lift in the DGZ due to the CCB.  So many acronyms, I'm sorry.  Unfortunately, it doesn't last long, and the best rates appear to diminish quickly as the heaviest band moves hurriedly to the east.

If you're a snow watcher, that means the best rates will be in the dark, though the onset of precip doesn't look bad.  The heaviest stuff barely avoids PIT metro for a while and looks to bury Westmoreland/Armstrong/Indiana counties, for example.  I suppose that's not unusual.

There's also a time between 7 and 9 PM where PIT gets very close to sleeting due to southeasterlies above the surface, brought on by (I believe) extreme frontogenesis.  This also kills the lift in the DGZ for a little so there might be a minor lull in snowfall rates.  This is extreme over-analysis of one run, but it gives a bit more detail about one possibility as to what could occur.

Glossary - 

DGZ - Dendritic Growth Zone (upper atmosphere where snowflake growth is achieved most efficiently; see graphic below)

CCB - Cold Conveyor Belt (an aspect of "occlusion" that transports cool, moist air westward around the center of low pressure; "comma head")

morphologydiagram.jpeg

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1 hour ago, ChalkHillSnowNut said:

What’s that little tongue of reduced totals in fayette county? Is that mixing issues or the LP transferring energy right there?....

Basically the "dry conveyor belt" as the low pressure center begins to mature and occlude, forming that traditional "comma" shape.  You can look at a comma and see how there's a natural space between the head and the tail.

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4 minutes ago, Rd9108 said:

Lmao we go from worrying about missing to the east to the dreaded warm tongue of death showing up. Let's see what the other models do. 

We always have to worry about something. If the trends keep up when do you think they take us from a watch to a warning? After the full 12z suite of model runs?

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5 minutes ago, Rd9108 said:

Lmao we go from worrying about missing to the east to the dreaded warm tongue of death showing up. Let's see what the other models do. 

This is how we do our big ones, we watch the mix line slowly creep towards us on radar. 

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1 minute ago, north pgh said:

We went from being fringed with 2-4 to a possible foot with some mixing issues and people are complaining?

Even if I get 6-10 and have to mix for an hour or two I will take it.

BTW I think that the mixing will be minimal if any.

Oh I agree. Three days ago this looked like we were gonna get 3 inches if we were lucky. I honestly don't care as much as the total, I just want to see some heavy heavy snow. 

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Wow, the 12Z NAM doesn't back off.  That's incredible.  The last time I remember the NAM scoring a coup was 2016, when it was north of all of globals, then with 24-36 hours left, all the globals came north to the NAM.  I'm not buying just yet, but I've got my wallet out.

Even with the Ferrier correction on the 3K, Pittsburgh metro gets a foot.  It shifts the jackpot from Harrisburg to Lock Haven, which isn't insignificant (about 70 miles).  If PIT gets under the CCB as it forms along the axis, it could happen, but that's relying on a very specific feature.

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12 minutes ago, jwilson said:

Wow, the 12Z NAM doesn't back off.  That's incredible.  The last time I remember the NAM scoring a coup was 2016, when it was north of all of globals, then with 24-36 hours left, all the globals came north to the NAM.  I'm not buying just yet, but I've got my wallet out.

Even with the Ferrier correction on the 3K, Pittsburgh metro gets a foot.  It shifts the jackpot from Harrisburg to Lock Haven, which isn't insignificant (about 70 miles).  If PIT gets under the CCB as it forms along the axis, it could happen, but that's relying on a very specific feature.

That banding can be iffy, but definitely can lead to overperforming storms. That 11” we got in March a couple years ago had that. 

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9 hours ago, blackngoldrules said:

Well, I haven't posted here in a while, but trying to get back into the hobby again. Losing my wife last year messed with me in so many ways, but I'm trying to find joy in my old hobbies again and this was definitely one of them. Anyway, I've been checking out the models today and I do like our trend as of now. Definitely an advisory event and trending toward hopefully a WSW. Last winter was a complete dud. Not that I cared personally as I just wasn't into it, but maybe this winter will be a little better for us. Already one good event so far and the possibility of another before winter officially begins. Anyway, missed you guys and missed this page.

So sorry to hear about your loss, can't even pretend to understand how that would affect you on so many levels. Glad you are back and I hope you can enjoy tracking with us again. Looks like we may be on the verge of snatching victory from the jaws of defeat on this next one. :)

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22 minutes ago, north pgh said:

We went from being fringed with 2-4 to a possible foot with some mixing issues and people are complaining?

Even if I get 6-10 and have to mix for an hour or two I will take it.

BTW I think that the mixing will be minimal if any.

I tend to agree. This isn’t like a WTOD where it overwhelms with a strong inland storm. It should flip back even if there is a period of slop.

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1 minute ago, KPITSnow said:

My call...6-10 county wide...more East side of county so I could see like Freeport maxing out. 

I’m thinking 6-8 here in chalk hill-even tho I’m at 2100 elevation, that low transfer thing or mixing seem to be affecting my totals....we’ll see! Happy you all are in the big game now!! 

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