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February 18-19 Event


hazwoper
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29 minutes ago, The Iceman said:

Paul, is the wxsim usually pretty good at picking up the sneaky warm layers? That seems like a really low forecast based on the models and usually when you post it, it's on the high end of guidance. Do you think it's a red flag that it's showing mostly sleet?

Yes - this has all the earmarks of a sleet fest....let's see if it changes when the 12 z GFS gets added to the mix - this forecast was combo of 6z GFS and 12z NAM

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3 minutes ago, ChescoWx said:

Yes - this has all the earmarks of a sleet fest....let's see if it changes when the 12 z GFS gets added to the mix - this forecast was combo of 6z GFS and 12z NAM

If it was sleety already I’d expect it to get worse with the GFS. I feel more confused than I did yesterday. Huge potential but even high end is around 6” or so. Sucks because there was a period after 12z runs yesterday I started to feel like 6-10 was legit

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12 minutes ago, Birds~69 said:

Accu weather at noon shifted the heavier snow SE  (closer to Philly) from their prediction earlier this morning...

noon aw.jpg

Let's stop the hedging and just get right to it here.  Areas along I-95 if no warm layer at 5,000 to 7,000 feet 6-9" if there is a warm layer we are looking at 3-4" with a flip to sleet 1-2" of that possibly followed by 0.10-0.20" of freezing rain depending on the warming aloft.  I would at this point lean more towards a 50/50 mix of all the models and go with the 3-5"+ idea.  So. We are almost at the point of letting it play out.  Obviously less south and east into coastal New Jersey and south in Delaware. 

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4 minutes ago, Birds~69 said:

The thing about that model which doesn't make sense is Philly burbs and far burbs don't exceed 6"?

I find that model seems to be much better at focusing on region-wide averages.  It will typically not have some of the crazy jackpot zones that other models have.

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15 minutes ago, Mshaffer526 said:

I find that model seems to be much better at focusing on region-wide averages.  It will typically not have some of the crazy jackpot zones that other models have.

That makes more sense as a average.

Somehow Allentown will receive 10"+ though....they are a snow magnet.

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My bar is set at 6", so I can live with the Euro. I don't think qpf will be an issue, aren't we tapping gulf moisture? I think it's more a question of snow vs non-snow. But what do I know? As was stated earlier, this was a lakes cutter last week. Anything other than rain is a win.

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22 minutes ago, The Iceman said:

Euro says all systems go, should be fun from 7 am - 1 pm tomorrow. Not much mixing at all along 95.

 

sn10_acc.us_ne.png

Couldn't ask for a better spot for the pink stuff. Iit pretty much covers the majority of this subforum.

What happens after 1pm or so....spotty light stuff till the end?

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Just now, Birds~69 said:

Couldn't ask for a better spot for the pink stuff. Iit pretty much covers the majority of this subforum.

What happen after 1pm or so....spotty light stuff till the end?

Yeah looks like we go over to light precip after that but should still linger another 12 hours or so.

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1 minute ago, Lady Di said:

Will the watch change this afternoon to a warning?  Already issued down south

Absolutely will change from a Watch to a Winter Storm warning probably for 4-8" in lower SE PA with some sleet and freezing rain too to be thrown in to cover the uncertainty of the warm layer at 5000 to 7000 feet.

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My current call for the city is 4-7", including a fair amount of sleet, and .1-.2" of ice. This is based on a blend of the RPM and other model guidance (and history of model performance this season wrt mid level warmth). I don't buy all snow. RPM does show a consistent change to sleet and then FZRA on every run. How much the snow total ends up being hinges on how fast mid level warm air comes in...but we will enjoy at least a couple hours of good rates. And I will abs take that. 

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Just now, Moderately Unstable said:

My current call for the city is 4-7", including a fair amount of sleet, and .1-.2" of ice. This is based on a blend of the RPM and other model guidance. I don't buy all snow. RPM does show a consistent change to sleet and then FZRA on every run. How much the snow total ends up being hinges on how fast mid level warm air comes in...but we will enjoy at least a couple hours of good rates. And I will abs take that. 

When do you think the best rates will hit?

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7 minutes ago, yankeex777 said:

When do you think the best rates will hit?

At the moment, my thinking is the Philly area sees 1-2" rates between 10AM-1PM. We may pick up 1-2 inches before that time but that's really the "main" period I'm focused on. As we head into the mid afternoon sleet becomes much more likely. 

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10 minutes ago, Moderately Unstable said:

My current call for the city is 4-7", including a fair amount of sleet, and .1-.2" of ice. This is based on a blend of the RPM and other model guidance (and history of model performance this season wrt mid level warmth). I don't buy all snow. RPM does show a consistent change to sleet and then FZRA on every run. How much the snow total ends up being hinges on how fast mid level warm air comes in...but we will enjoy at least a couple hours of good rates. And I will abs take that. 

When does the RPM generally change the city/95 over to sleet/frz? Also it seems like you think freezing rain will end up being a bigger deal than what's being currently talked about. .1-.25" of freezing rain on top of 3-4" of snow would be more impactful than an all snow 6-8" event imo. Do you think we will see a deeper warm layer than forecasted? Most guidance I've seen, it looks fairly shallow and leans more towards it falling as sleet with the low level cold in place but I definitely would like to hear your thoughts on that.

 

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Just now, The Iceman said:

When does the RPM generally change the city/95 over to sleet/frz? Also it seems like you think freezing rain will end up being a bigger deal than what's being currently talked about. .1-.25" of freezing rain on top of 3-4" of snow would be more impactful than an all snow 6-8" event imo. Do you think we will see a deeper warm layer than forecasted? Most guidance I've seen, it looks fairly shallow and leans more towards sleet imo but I definitely would like to hear your thoughts on that.

 

It's aggressive on the changeover...it blasts us with WAA in the mid levels as the coastal approaches. The 12z run held us in the snow camp a bit longer than the 15z run...but on the order of 30 minutes: 1800 vs 1830z. I do very much think FZRA will be a bigger deal--I agree on the impacts...BUT that sort of also depends on the time of day it's falling. Messy-yes, but at 30/31 degrees in the late afternoon it won't be as bad as if it fell overnight with temps in the 20s. If you compare the SREF probabilities for us for ptypes...

https://www.spc.noaa.gov/exper/sref/srefplumes/

 

Or you look at the HREF's probabilities for heavy snow, fzra etc:

https://www.spc.noaa.gov/exper/href/?model=href&product=snowfall_001h_prob01&sector=conus

 

And for me combined with the RPM, GRAF, and other guidance...it's really all different flavors of the same thing that we are being told. We know that models have had a cold bias this season, and it would be quite hard to believe in this setup, with the position of the coastal and the 850....that this isn't a "mess" type of event. That doesn't mean the front end won't be fun though. I don't necessarily think we'll see a quarter inch of ice, but looking back at the history this season when it comes to mid level warmth, my money would be on the warmth winning relative to expectations. 

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23 minutes ago, Moderately Unstable said:

My current call for the city is 4-7", including a fair amount of sleet, and .1-.2" of ice. This is based on a blend of the RPM and other model guidance (and history of model performance this season wrt mid level warmth). I don't buy all snow. RPM does show a consistent change to sleet and then FZRA on every run. How much the snow total ends up being hinges on how fast mid level warm air comes in...but we will enjoy at least a couple hours of good rates. And I will abs take that. 

What are you thoughts for Berks?

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