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One More Shot: Feb 20-21 Event


Tar Heel Snow
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1 minute ago, CentralNC said:

Yeah i'm not really feeling it here in the western piedmont.  Check out DT's FB first call.  I think he has way to much in western piedmont and foothills of NC.

Don't believe it is as bad on the short range models and this is really not ideal range for GFS is it?

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16 minutes ago, CentralNC said:

Yeah i'm not really feeling it here in the western piedmont.  Check out DT's FB first call.  I think he has way to much in western piedmont and foothills of NC.

DT seems way too bullish to me.  I've noticed this before also.  This isn't a perfect winter storm setup, if there even is such a thing anymore.  Therefore, IMO, it's unwise to forecast near maximum possible snow accumulations.

If we assume .5 qpf in Raleigh, which I don't think is unreasonable, you have to account for at least some rain and mixed precipitation.  And that usually ends up being more than forecast by the pretty snow maps.  That leaves about 2-3 tenths to fall as all snow.  So, 2, maybe 3 inches seems within the ballpark of reasonable. 

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1 hour ago, burrel2 said:

Big shift south with the R/S line on the latest Hrrr... caveat, above this line isn't snow if your low level temps are too warm for it to reach the ground. Also it's even slower with precip arrival. Valid 10am tomorrow morning

Sounding is for Clemson, SC at 10am.

Screen Shot 2020-02-19 at 6.25.21 PM.png

Screen Shot 2020-02-19 at 6.26.25 PM.png

Ouch though, at the temp of 44. Looks like that warm nose is just enough to cause some mixing, maybe it will erode quickly. My temp is 48 now so not looking good for BL temps. 

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1 minute ago, Extreme NEGA said:

He nailed our 2/8 storm though.

I'm not saying he's wrong necessarily, but anybody whose hyping magical blizzards from months out gets an automatic unfollow from me. And that was a much easier storm to forecast because the cold air was not a concern at any layer in the atmosphere. 

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4 minutes ago, Iceagewhereartthou said:

Ouch though, at the temp of 44. Looks like that warm nose is just enough to cause some mixing, maybe it will erode quickly. My temp is 48 now so not looking good for BL temps. 

NAM is often too warm at the surface. Not saying it is this time, but it was atrocious for lower level temps in GA 2 weeks ago. 

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1 minute ago, SnowDawg said:

I'm not saying he's wrong necessarily, but anybody whose hyping magical blizzards from months out gets an automatic unfollow from me. And that was a much easier storm to forecast because the cold air was not a concern at any layer in the atmosphere. 

the blizzard isn't happening lol

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Just now, SnowDawg said:

NAM is often too warm at the surface. Not saying it is this time, but it was atrocious for lower level temps in GA 2 weeks ago. 

Yeah I remember that too, something like +5 for many areas. No clearing for western areas tonight doesn't help though, many eastern areas seeing some clearing for a bit.

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Just now, Iceagewhereartthou said:

Yeah I remember that too, something like +5 for many areas. No clearing for western areas tonight doesn't help though, many eastern areas seeing some clearing for a bit.

Temps are fully dependent on how much lower level cold/dry air can get pumped in before go time. HRRR struggles badly with wet bulbing as well as oddly warming the surface in the heart of events with precip falling through an isothermal column. Without a stout warm surface wind that just simply isn't going to happen. 

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14 minutes ago, Iceagewhereartthou said:

Ouch though, at the temp of 44. Looks like that warm nose is just enough to cause some mixing, maybe it will erode quickly. My temp is 48 now so not looking good for BL temps. 

I'm not concerned with low level temps on the HRRR, i know it has a warm bias. Also, precip hasn't started on that panel so no wetbulb or top down cooling has started on that panel.

I'm much more concerned with the 800mb warm nose, and the HRR looks promising from that standpoint. 

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1 minute ago, burrel2 said:

I'm not concerned with low level temps on the HRRR, i know it has a warm bias. Also, precip hasn't started on that panel so no wetbulb or top down cooling has started on that panel.

I'm much more concerned with the 800mb warm nose, and the HRR looks promising from that standpoint. 

And the 800mb warm nose can and will be a killer if it decides to show up. 

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Probabilistic Heavy Snow and Icing Discussion  - NWS Weather Prediction Center - College Park MD 325 PM EST Wed Feb 19 2020

Southern Appalachians and Mid Atlantic... Days 1-2... Guidance coming into much better agreement this afternoon in the evolution of a positively tilted upper trough and surface low affecting the Southern Appalachians and into NC/VA. Outside of the NAM, there is good consensus that mid-level WAA ahead of the upper trough will spread moisture northeast across the area atop a surface cold front which will sag into South Carolina and off the coast. At the same time, jet streak energy will merge and intensify to 170+kts as it exits near New England, leaving the diffluent RRQ atop the Carolinas, supporting ventilation to lower pressure and spawn cyclogenesis along the baroclinic zone offshore. The combination of all these features will produce widespread precipitation across the area, with cold air advection slowly transitioning p-type from rain to snow. The low-level thermal profile will be marginal, and antecedent conditions are unfavorable to snow accumulations, however, robust forcing, especially within an intensifying mid-level frontogenetic band pivoting across NC/VA will overcome these marginal conditions to produce a period of heavy snow. The most likely locations for heavy snowfall exceeding 4 inches will be in the terrain of NC/TN, with a secondary maximum possible in northeast NC where the longest duration of precipitation falling into the colder air will occur. Additionally, guidance indicates the potential for a band of snow to rotate eastward as the low pulls away Friday morning, which could also enhance snowfall locally. WPC probabilities for 4 inches are around 20% in the mountains, and 30-40% in northeast NC/far southeast VA.

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Just now, Extreme NEGA said:

HRRR is too warm.

At the surface. But it could also be too cold above. Warm noses are almost never forecasted well. IMO we won't know how strong it is or where it sets up until it does. We've basically exhausted what the models have to offer us, time to start now-casting. 

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3 minutes ago, SnowDawg said:

At the surface. But it could also be too cold above. Warm noses are almost never forecasted well. IMO we won't know how strong it is or where it sets up until it does. We've basically exhausted what the models have to offer us, time to start now-casting. 

If there is one, the NAM will nail it. Back in 14, the Euro was spitting out 20” totals , and every one was giddy, then about 12 hours out, people said, watch out, the NAM is showing a warm nose, and there will be a lot of sleet! I got 1” of sleet

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Well grasping at straws down here:lol: How good are the WRF models? Do they tend to over do the cold? One gives me 2 inches and another 4. I would be happy with that.

I hear you. We have a WWA in Pickens County (GA) and each time anyone mentions a movement south, I get more excited.


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4 minutes ago, mackerel_sky said:

If there is one, the NAM will nail it. Back in 14, the Euro was spitting out 20” totals , and every one was giddy, then about 12 hours out, people said, watch out, the NAM is showing a warm nose, and there will be a lot of sleet! I got 1” of sleet

Hmm. In another thread I asked what time our hopes usually get crushed and you said “yesterday”.

On topic: Durham county schools closed tomorrow per WRAL. Wake starts 3 hours late.

Relurks

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