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January 3 CAPE Storm


WxUSAF
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Good news on the GFS for those of us to the NW is the expansion of the precip shield up into central PA. I figured we would start seeing that as the model runs closer the event came in. Still think the the battleground is further SE than normal and we dont end up seeing a death band out this way. But getting skunked seems unlikely at this point as well. Just glad we are actually about to see a decent region wide storm in a Nina. Enjoy everyone. 

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5 minutes ago, Solution Man said:

First Winter in Haymarket….let’s see how we fair

We often make dramatic showings that fall just short here in west Prince William County… The only place worse is East Prince William County… But welcome

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https://www.tropicaltidbits.com/sat/satlooper.php?region=us&product=wv-mid

The WV loop is a thing of beauty. The flow is really backing in the TN valley. This has a classic look for the mid Atlantic!

Btw I still like to look at the WV sometimes just to get a feel for the flow. I’ll never forget being in the psu weather center the day before the Jan 2000 storm trying to argue with the meteorologists on duty that it was clear from the WV and IR that the mid and upper levels were way more amplified and the flow was backing much more than any of the nwp was showing over the Miss Valley.  They were pretty dismissive…”it’s only 24 hours, the models would be picking up on it”  lol  

 

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8 minutes ago, snowfan said:

Certainly reason to keep expectations in check wrt max accumulation. Warm ground temps + wetness will eat up some initial accums. Rates will overcome but I wouldn’t be expecting double digits.

The 'warm ground' theory has been debunked numerous times, most notably out west (CO front range, temps in the 70s one day, blizzard the next), but even here in the mid Atlantic as well. Especially along the coast (see Norfolk with the March 1980 snowstorm). 

Your point about the rates is spot on. Best case scenario I see is we crash to 32 with ripping fat flakes.  There is certainly some instability, or very weak stability, to work with within the dendritic growth zone. 

Screenshot_20220102-111654_Chrome.jpg

Screenshot_20220102-111730_Chrome.jpg

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38 minutes ago, CAPE said:

GFS has locked in on the big storm idea for 4 straight runs now, e incrementally better. Gotta go with it. B)

Impressed that the GFS was the best (by far) handling H5 in the mid range. I got dragged in when the first few runs hit showing h5 closing off just east of the MS River in the deep south. That's part of our textbook here with southern stream shortwaves. Too soon = rain. Too late = furries or cirrus. Just right? Gfs is perfection, basically 

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Hmmm, perhaps I should stay at my brother’s house in Ellicott City another night instead of heading back up to my house in Carroll County. I am off until Tuesday anyway! Looks like a better spot to be for this one (first time I’ve said this in several years)

excited for you all in the southern half of the CWA!

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With my homemade python program which takes in the EURO, GFS, CMC and ICON input then weights each differently (EURO then CMC then GFS then ICON), it spit out a raw output of 6.93 not factoring in melt or anything. Fed the program 7, 15, 5, 0 for amounts so glad to see the output is somewhat realistic. 

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1 minute ago, Bob Chill said:

Impressed that the GFS was the best (by far) handling H5 in the mid range. I got dragged in when the first few runs hit showing h5 closing off just east of the MS River in the deep south. That's part of our textbook here with southern stream shortwaves. Too soon = rain. Too late = furries or cirrus. Just right? Gfs is perfection, basically 

So good to see you here my friend. Gfs truly is a thing of a beauty, and it’s been pretty damn consistent the past few days. 

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6 minutes ago, WxMan1 said:

The 'warm ground' theory has been debunked numerous times, most notably out west (CO front range, temps in the 70s one day, blizzard the next), but even here in the mid Atlantic as well. Especially along the coast (see Norfolk with the March 1980 snowstorm). 

Your point about the rates is spot on. Best case scenario I see is we crash to 32 with ripping fat flakes.  There is certainly some instability, or very weak stability, to work with within the dendritic growth zone. 

Screenshot_20220102-111654_Chrome.jpg

Screenshot_20220102-111730_Chrome.jpg

Can you point to a reference on the warm ground debunking?  Not arguing, I'm genuinely interested in reading more on it.  My experience is the warm ground makes a 1" layer of slush but on top of that it's all snow. 

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12 minutes ago, IronTy said:

Can you point to a reference on the warm ground debunking?  Not arguing, I'm genuinely interested in reading more on it.  My experience is the warm ground makes a 1" layer of slush but on top of that it's all snow. 

Most of the long timers here debunked it through experience. All the doubt and hand wringing leading in then "shock and awe" that it stuck. IME, it usually comes down to the start. We all know the ground won't be frozen at all so how does it still pile up? Gotta get a quick start. Miller A's are good at that because the front side WAA snow usually comes in hot and heavy. It has to, otherwise the Pacman starts eating and never stops. 

If the front piece comes in in pulses and lulls...that's trouble. I've lost half of a storms qpf to melt/nonstick away too many times. 1"/hr rates at night will stick no problem above freezing. Gotta get the blanket down to maximize the cold side of the storm. March 2013 is a great example of how you get screwed even when qpf is good enough.

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23 minutes ago, IronTy said:

Can you point to a reference on the warm ground debunking?  Not arguing, I'm genuinely interested in reading more on it.  My experience is the warm ground makes a 1" layer of slush but on top of that it's all snow. 

I think the cooling due to conduction, i.e. with cold rain at the outset, does a great deal pretty quickly. We often see road surface temps fall into the 30s pretty quickly. But you're absolutely correct -- that first layer would be slush, and overall, the depth of snow on the roads in this setup would be less than that over non-paved surfaces. Would be a mess to drive on. 

Like you all have said, it's a "rates" storm. We absolutely need that or it's essentially a non-event. Much like November 11th 1987. When it happens, it's a think of beauty. A pasty wet snowfall -- my favorite -- with clumping aggregate flakes. A low probability event to be sure, but we've got the setup going for us, as well as a consensus among most models now within 24 hrs of the event. 

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2 minutes ago, Bob Chill said:

Most of the long timers here debunked it through experience. All the doubt and hand wringing leading in then "shock and awe" that it stuck. IME, it usually comes down to the start. We all know the ground won't be frozen at all so how does it still pile up? Gotta get a quick start. Miller A's are good at that because the front side WAA snow usually comes in hot and heavy. It has to, otherwise the Pacman starts eating and never stops. 

If the front piece comes in in pulses and lulls...that's trouble. I've lost half of a storms qpf to melt/nonstick away too many times. 1"/hr rates at night will stick no problem above freezing. Gotta get the blanket down to maximize the cold side of the storm. March 2013 is a great example of how you get screwed even when qpf is good enough.

Good point, I agree on the pulsing.  It's gotta push during the onset to build up a slush layer.  If it comes and goes it ends up as an inch or two of slush.  This is what happened during last winter's storm for us.  Even during snowmageddon we had a solid inch of slush underneath.  

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