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Presidents Day storm Part 2

Ji

By Ji,
in Mid Atlantic

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mitchnick

mitchnick

Posted
Posted

A 10% probability of receiving 4" or more is not very high. Have to understand what the product is telling you.

I'm not talking about today in my critique, I was talking about the lousy performance of the product/forecast within 24 hours of our last event. And your backhanded effort to disparage me was as poor as that forecast with that product last week.
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WxMan1

WxMan1

Posted
Posted

One thing about the WPC prob maps...

Keep in mind the image provided is valid from 12Z Mon-12Z Tue. It does not take into account anything before 7 am Mon, which would explain those <10% probs of 4" or more. The NAM, already has 0.1"+ precip by 12Z.

The probabilities that will come out later today, valid from 00Z Mon - 00Z Tue, will encompass the entire period of snow, so I would expect the 4" probs to be higher than 10% (though probably still less than 40%).

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ers-wxman1

ers-wxman1

Posted
Posted

I'm not talking about today in my critique, I was talking about the lousy performance of the product/forecast within 24 hours of our last event. And your backhanded effort to disparage me was as poor as that forecast with that product last week.

Just about every product ever made was a bust for last weeks event.

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psuhoffman

psuhoffman

Posted
Posted

The second wave that had been mentioned is about to catch the first one on the gfs.

the spacing isn't enough. That wave is actually phasing in partially and helping to pull this northwest more. If it was 24 hours slower this might have been better and or that might have had a chance on its own. Seems we have been just a bit off on timing a lot this year. Some patterns we just have no chance. Some are so good it's hard not to snow. For most of the time since jan 10 or so we have had a good but somewhat flawed pattern. One where we have chances but need some luck with timing. And for the most part we have been dealt a bunch of crap cards each hand.
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ers-wxman1

ers-wxman1

Posted
Posted

Well, had you just posted that admission instead of starting with personal attacks out of left field, things would have gone a whole lot smoother.

I don't post personal attacks in this forum!! Over and over I have to explain this. It's how you are reading into it. I'm merely explaining the product and its intended use.

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Snowman.

Snowman.

Posted
Posted

the spacing isn't enough. That wave is actually phasing in partially and helping to pull this northwest more. If it was 24 hours slower this might have been better and or that might have had a chance on its own. Seems we have been just a bit off on timing a lot this year. Some patterns we just have no chance. Some are so good it's hard not to snow. For most of the time since jan 10 or so we have had a good but somewhat flawed pattern. One where we have chances but need some luck with timing. And for the most part we have been dealt a bunch of crap cards each hand.

You just got 6" from that fluke event last week while most of us got less than an inch.  ;)

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WxMan1

WxMan1

Posted
Posted

The WPC maps are more for guidance purposes and dovetail well for WFO's and their perspective watch/warning/advisory criteria. They are also a blend of many different guidance members combined so not really a deterministic product...more probabilistic.

Exactly. They include a deterministic component, which serves as the "mode" for a 57 member ensemble that include the deterministic runs along with SREF, GEFS, and EC members. This is a fixed system, one which we (WPC forecasters) cannot post edit. If we see a problem with the probs, then we need to go back and edit the deterministic output first, then re-run the probs. We are discouraged to post edit those "final" probs that were posted earlier in this thread. Otherwise, there would be an inconsistency with the PWPF graphics found at

origin.wpc.ncep.noaa.gov/pwpf/wwd_accum_probs.php?fpd=24&ptype=snow&amt=1&day=1&ftype=probabilities

Now, the deterministic snow and ice output done at WPC stays internal, used to derive the probability grids and also sent to the WFOs as guidance. We (WPC) don't make the forecast snow and ice accumulations public because NDFD is the official NWS forecast.

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BTRWx

BTRWx

Posted
Posted

One thing about the WPC prob maps...

Keep in mind the image provided is valid from 12Z Mon-12Z Tue. It does not take into account anything before 7 am Mon, which would explain those <10% probs of 4" or more. The NAM, already has 0.1"+ precip by 12Z.

The probabilities that will come out later today, valid from 00Z Mon - 00Z Tue, will encompass the entire period of snow, so I would expect the 4" probs to be higher than 10% (though probably still less than 40%).

Thank you. That makes so much more sense.

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Bob Chill

Bob Chill

Posted
Posted

I so want to call out the people who were hugging the Canadian because it was 'steady'... lololol. Model regurgitation is the new forecasting.

In this case I thought it was pretty easy to hug the euro once it barely wavered for 4 runs in a row inside of 84-96 hours. It's pretty deadly when you see that happen with a few exceptions of course. Overall the euro made complete sense given the synoptic patten

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mattb65

mattb65

Posted
Posted

Ideal ice accretion occurs with temps below 30 and light precip over longer periods of time. Steady drizzle or light rain is best for icing. Heavier precip runs off.

I think for really significant icing, you also need a dew point depression as well as a constant feed of low level cold air. Relying on in situ CAD with a retreating high pressure automatically limits your cap on ice accretion due to latent heat release.

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psuhoffman

psuhoffman

Posted
Posted

You just got 6" from that fluke event last week while most of us got less than an inch. ;)

yes but this forum is Baltimore Washington based and I'm not focusing on my backyard when I say "we". If I post in the interior thread then I would have a different tone. I still like it here because when I started on the forums I lived in northern va and got used to the people in here plus I think this is one of the most realistic and knowledgable regions so I try to take a more inclusive view of things when in here. I'm one of the snowier locations in this region but I would like to see us all do well. I don't root against dc when it's going to snow. I'd love an event like snowzilla where we all get to be happy.
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Ian

Ian

Posted
Posted

In this case I thought it was pretty easy to hug the euro once it barely wavered for 4 runs in a row inside of 84-96 hours. It's pretty deadly when you see that happen with a few exceptions of course. Overall the euro made complete sense given the synoptic patten

Yes, agreed. Especially with two Euros. They should keep running both versions. :P

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usedtobe

usedtobe

Posted
Posted

I so want to call out the people who were hugging the Canadian because it was 'steady'... lololol. Model regurgitation is the new forecasting.

 

It's hard to beat the euro and its clones thoough for surface temps, I do worry a little about the NAM which holds onto the cold air longer than the GFS or Euro.  I don't believe its snow forecast but worry about its icing forecast even though it has slowly edged towards the warmer contingent.

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Ian

Ian

Posted
Posted

It's hard to beat the euro and its clones thoough for surface temps, I do worry a little about the NAM which holds onto the cold air longer than the GFS or Euro.  I don't believe its snow forecast but worry about its icing forecast even though it has slowly edged towards the warmer contingent.

It's definitely worth considering at this point. I like the NAM more than a lot of folks here based on comments. I just find it funny the same people who rail against it so frequently are willing to favor it when it shows what they are looking for. Today's runs in particular should probably be weighted on temps to at least some degree (haha!). ;) 0z especially .. if it it still extra cold I'd probably bite harder myself.

 

I realize I'm kind of a jerk sometimes esp when making short quips. I spend as much or more time on Twitter these days so I sometimes mix my commentary by accident. The usual suspects have been fair and balanced like always. Just seemed I've noticed more hopeful filler in recent times overall. I also do get the feeling that across the enterprise there is more run to run shift than ever and I don't think it's that good of a thing. Usually a trend day to day will be rather slow and methodical whereas you see bigger jumps run to run. Like taking every GFS blip as a reason to really think about the solution even though it's unlikely because it's a blip etc.

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BTRWx

BTRWx

Posted
Posted

It's definitely worth considering at this point. I like the NAM more than a lot of folks here based on comments. I just find it funny the same people who rail against it so frequently are willing to favor it when it shows what they are looking for. Today's runs in particular should probably be weighted on temps to at least some degree (haha!). ;) 0z especially .. if it it still extra cold I'd probably bite harder myself.

 

I realize I'm kind of a jerk sometimes esp when making short quips. I spend as much or more time on Twitter these days so I sometimes mix my commentary by accident. The usual suspects have been fair and balanced like always. Just seemed I've noticed more hopeful filler in recent times overall. I also do get the feeling that across the enterprise there is more run to run shift than ever and I don't think it's that good of a thing. Usually a trend day to day will be rather slow and methodical whereas you see bigger jumps run to run. Like taking every GFS blip as a reason to really think about the solution even though it's unlikely because it's a blip etc.

I find it funny how many folks have been wanting to jump ship for this. I'm loving what we're seeing with the cad signals!

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Bob Chill

Bob Chill

Posted
Posted

I find it funny how many folks have been wanting to jump ship for this. I'm loving what we're seeing with the cad signals!

Seems like a lot of folks were hanging onto the weaker/east solution and thinking a decent snow storm was on the table. I never really saw that Tbh and I usually hedge optimistic more often than not. It's pretty much playing out as the most logical scenario.

It qualifies as an "event" for just about everyone. Given how tough it's been to line stuff up this year we should consider this one a win to some degree if we get a couple inches of snow on cold ground. At least we aren't completely wasting the coldest air of the year it seems

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psuhoffman

psuhoffman

Posted
Posted

I find it funny how many folks have been wanting to jump ship for this. I'm loving what we're seeing with the cad signals!

expectations are different. I think some, especially nw of the cities like Winchester to Frederick were still holding out hope this was something more then 2-4" then rain. To me it looks more like 1-3 then rain but that's not worth getting into but if you were holding out hope for a more significant event like the gfs runs of two days ago or several ggem runs then it's time to throw in the towel.

ETA: ninjad by Bob

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