Ice Time? Dec. 16ish Possible CAD Event

[AirNelson39]

[BooneWX]

Nam looks like a bit more ice for western NC down into the upstate since most areas are at .25+ with the model still showing freezing rain at hour 84. Colder air seemed a little deeper that run. 

[JoshM]

Just now, BooneWX said:

Nam looks like a bit more ice for western NC down into the upstate since most areas are at .25+ with the model still showing freezing rain at hour 84. Colder air seemed a little deeper that run. 

High Res NAM is a touch colder than 12km, dewpoints are colder as well

[JoshM]

I know it's hour 60, but

[JoshM]

Going to be a very close call south of I-40, I would pay attention to High Res NAM. IMO, it handles the CAD better

[jjwxman]

Going to be a very close call south of I-40, I would pay attention to High Res NAM. IMO, it handles the CAD better

I’m fully prepared for 32.4 degrees and rain in Randleman. (15 miles south of GSO)


.

[wncsnow]

The RDPS looks similar to past runs. Maybe a bit more moisture 

[SnowNiner]

53 minutes ago, JoshM said:

Going to be a very close call south of I-40, I would pay attention to High Res NAM. IMO, it handles the CAD better

Those dew points are just not very cold. I can't get past that. Hope the 3K tomorrow will see it a bit colder tomorrow.

[Blue_Ridge_Escarpment]

The 3k NAM is very concerning for the eastern side of the Blue Ridge. 

[ILMRoss]

Two things to keep in mind:

-There is some scientific backing behind "hi-res models do better with CADs", which at face value can scan as a weenie-ism sometimes. Hi-res models will have a  much more detailed rendering of the apps and topography in general- as it turns out when forecasting a topographically-induced weather event, having the topography rendered as accurately as possible is important!

-I have never, in 9 winters of lurking and posting through this board, seen ZR qpfs be accurate. They are almost always inflated. The only legitimate ice storms I can really remember that mildly panned out were all in 2014.

[rowjimmy73]

2 minutes ago, ILMRoss said:

Two things to keep in mind:

-There is some scientific backing behind "hi-res models do better with CADs", which at face value can scan as a weenie-ism sometimes. Hi-res models will have a  much more detailed rendering of the apps and topography in general- as it turns out when forecasting a topographically-induced weather event, having the topography rendered as accurately as possible is important!

-I have never, in 9 winters of lurking and posting through this board, seen ZR qpfs be accurate. They are almost always inflated. The only legitimate ice storms I can really remember that mildly panned out were all in 2014.

im 4 years into southern winters and have never seen one here in danville either. ive heard about them from a friend and they dont sound fun at all. that being said i see wpc has us between .10 and .25 realistically towards the lower end. hoping the high presses a bit more since i stocked up on batteries and foods. 

 

 

[griteater]

28 minutes ago, ILMRoss said:

-I have never, in 9 winters of lurking and posting through this board, seen ZR qpfs be accurate. They are almost always inflated. The only legitimate ice storms I can really remember that mildly panned out were all in 2014.

But on Pivotal, the QPF (liquid) and ZR QPF are essentially the same amounts...so, they are just showing you how much precip will fall as freezing rain as opposed to how much ice accretion will occur.  I'd go with something like a 50% reduction for this storm given temperatures, warmth pre-storm, etc.  0.4 inches of liquid = 0.2 ice accretion.

Pivotal has added ice accumulation maps using the FRAM estimate with a paid subscription (I don't have one) - https://vlab.ncep.noaa.gov/documents/10157/137122/FRAM_VLAB_Presentation.pdf/50ff7877-c52d-80f4-1413-b294db7710e9

[ILMRoss]

5 minutes ago, griteater said:

But on Pivotal, the QPF (liquid) and ZR QPF are essentially the same amounts...so, they are just showing you how much precip will fall as freezing rain as opposed to how much ice accretion will occur.  I'd go with something like a 50% reduction for this storm given temperatures, warmth pre-storm, etc.  0.4 inches of liquid = 0.2 ice accretion.

Pivotal has added ice accumulation maps using the FRAM estimate with a paid subscription (I don't have one) - https://vlab.ncep.noaa.gov/documents/10157/137122/FRAM_VLAB_Presentation.pdf/50ff7877-c52d-80f4-1413-b294db7710e9

Yeah, I should of been more specific. "ZR qpfs" was a pre-coffee phrase. Meant calculated ZR totals... there's a variety of reasons it always happens, its not just a 'models have no idea how to handle this!' situation. It's always a dash of precip coming in an hour or two later than forecast, dews being a smidge higher than forecast, more sleet than ZR, things like that that can combine to eat in what forecasts say.

[griteater]

Just now, ILMRoss said:

Yeah, I should of been more specific. "ZR qpfs" was a pre-coffee phrase. Meant calculated ZR totals... there's a variety of reasons it always happens, its not just a 'models have no idea how to handle this!' situation. It's always a dash of precip coming in an hour or two later than forecast, dews being a smidge higher than forecast, more sleet than ZR, things like that that can combine to eat in what forecasts say.

Gotcha, yeah, true it is difficult to get the variables to all come together for a long duration freezing rain event from a big gulf low (like Dec 2002)

[Buddy1987]

Regardless 12z nam does not look fun wrt ZR potential. Right around .60 so even half of that would be pretty bad. Would say it’s kind of weird to see the nam so much warmer than gfs but reality is nam is super amped and gfs is more progressive in nature. Tough forecast at least for my area. If I were a betting man I’d probably go 2-4” then .15-.30 glaze 

[griteater]

1km NAM Radar scours out the cold pretty quickly, but should be some light icing

[Disc]

This is turning into a pure ice event in southern VA along the BR and foothills. A couple positives will be 1) the heavy rates will limit accretion. (2 coinciding marginal temperatures.

[griteater]

Canadian RDPS Trend Loop for 10AM Wed.  It has been quite consistent, but as typical, it is the coldest model.  I suspect it is a little too cold.  We will see

[Buddy1987]

36 minutes ago, Disc said:

This is turning into a pure ice event in southern VA along the BR and foothills. A couple positives will be 1) the heavy rates will limit accretion. (2 coinciding marginal temperatures.

Welp.. after seeing 12z gfs this is now the theme. Maybe we can get lucky and eek out 1-2” quick but looks to be a predominantly icy event here. 

[BornAgain13]

The Mid Atlantic will not like the GFS

[rowjimmy73]

7 minutes ago, BornAgain13 said:

The Mid Atlantic will not like the GFS

i know its kuchera but ill take 4 fantasy inches lol. i stil think its gonna be cold nuff to eek out some ice of merit. even ther gfs at 12z is still 6 hours of frozen just enough to cause issues in the hillier parts of pitts county and danville if it plays out. 

again this is all new to me , 35 years of nj winters and 9 florida, these last four have been a learning experience

 

[Joe Clark]

[BornAgain13]

I don't see how we even get an inch of snow here... not sure why the snow depth shows that?? The simulated radar only shows ice then rain here...

[Joe Clark]

8 minutes ago, BornAgain13 said:

I don't see how we even get an inch of snow here... not sure why the snow depth shows that?? The simulated radar only shows ice then rain here...

I assumed it shows everything frozen as snow....

[SnowNiner]

2 hours ago, griteater said:

Gotcha, yeah, true it is difficult to get the variables to all come together for a long duration freezing rain event from a big gulf low (like Dec 2002)

Agreed. You really need everything to line up right for a true problematic ice storm. December 2002 was the last one I remember that actually caused real problems IMBY. This week will likely not be anything close. Not enough qpf, not cold enough. All models seem to show eventually Wednesday everything turning to plain rain, washing away the glaze. 

2002 was something else though. Just pouring rain all night in the 20's. Dead silence in the morning, everything covered with ice, trees bent in half. 

[Buddy1987]

What did 12z euro show? I have limited access because of work.

[jjwxman]

I don't have access to the accumulated ice maps, but here is the only frame showing ice.  I-40 and north basically.

[Blue_Ridge_Escarpment]

Just now, jjwxman said:

I don't have access to the accumulated ice maps, but here is the only frame showing ice.  I-40 and north basically.

Euro folding like a cheap tent has become the norm these days. Colder each run. 

[jjwxman]

Next frame on the Euro.  Most of all NC goes over to a cold rain. 

[Buddy1987]

5 minutes ago, jjwxman said:

Next frame on the Euro.  Most of all NC goes over to a cold rain. 

Damn it’s way colder up this way.. I would not want to be Blacksburg for this one. Lose lose IMO