Freezing Rain, Sleet, Snow, Rain...Kitchen Sink (12/15-16)

[Myfrotho704_]

And since we're talking about CAD and warm noses and their model biases, it's worth noting that phenomena are, to some degree, two sides of the same coin. Perhaps somewhat counterintuitively, strong warm air advection above the boundary layer is really good for CAD. It creates a strong temperature inversion, which is really where the cold air at the surface derives its stability from. Because of that inversion, the cold air faces even more resistance if it tries to rise upward (over the mountain range).

In some ways, I wonder if the model bias of making CAD too weak has the same underlying reason as the bias to make warm noses too weak.

Really ready for the nam to come into range here, wonder if it can sniff out whether we’re gonna have a ice storm or whether we can get away with it with IP, my parents told me that dec 2002 storm was bad, I don’t remember it myself
Here’s to hoping we can somehow keep cooling that 925mb layer

 

[Brick Tamland]

Looking probable if not likely that somewhere in the Piedmont of NC and probably upstate of SC is going to see a major ice storm on Wednesday, whether or not that’s Greensboro, Charlotte, Raleigh-Durham, or Greenville-Spartanburg, &/or all of the above remains to be seen but I think someone is going to get clocked and it might be lights out

You think we could have ice this way? I thought we were just looking at rain. We haven't had a good ice storm here since 2002.

 

[Webberweather53]

Fyi, February 12-13 2014 featured a 1037 hPa high over Quebec & New England, ended up producing ice down in south-central Georgia (again obviously the air mass was a bit colder then too, arguably wouldn't bode well for parts of the Carolinas however)

Really, a parent sfc high > or = 1030 hPa is really strong for CAD.

 

[RVD]

Really ready for the nam to come into range here, wonder if it can sniff out whether we’re gonna have a ice storm or whether we can get away with it with IP, my parents told me that dec 2002 storm was bad, I don’t remember it myself
Here’s to hoping we can somehow keep cooling that 925mb layer

Yup, the NAM will be illuminating in this department for sure.

Actually, I think Dec. 2002 is my earliest weather memory. I lived in Chapel Hill at the time; I don't remember exactly how long it was, but our power was out for around a week.

 

[BHS1975]

I was outside fueling a private jet at RDU when that ice storm started and it was a steady rain with temps around 27 and when I saw a coat of ice form on my jacket sleeve within minutes I knew we where in trouble.


Sent from my iPhone using Tapatalk

 

[Webberweather53]

My prior experiences the last several years in tracking significant ice events like this says the CMC usually outperforms other global NWP models when it comes to CAD/Miller B setups, esp once the synoptic pattern is nailed down. The CMC's low-level cold bias actually benefits the model in not underestimating intensity of the CAD at least as much as say the GFS for ex.

Fwiw, there's a major ice storm for the upstate of SC & I-85 corridor in NC on the 0z CMC

 

[RainlessSnowless & Grumpy]

Fyi, February 12-13 2014 featured a 1037 hPa high over Quebec & New England, ended up producing ice down in south-central Georgia (again obviously the air mass was a bit colder then too, arguably wouldn't bode well for parts of the Carolinas however)

Really, a parent sfc high > or = 1030 hPa is really strong for CAD.

View attachment 57229

We had a lot more cold in the source region in 2014 correct?

 

[BHS1975]

My prior experiences the last several years in tracking significant ice events like this says the CMC usually outperforms other global NWP models when it comes to CAD/Miller B setups, esp once the synoptic pattern is nailed down. The CMC's low-level cold bias actually benefits the model in not underestimating intensity of the CAD at least as much as say the GFS for ex.

Fwiw, there's a major ice storm for the upstate of SC & I-85 corridor in NC on the 0z CMC

View attachment 57231

I'm guessing the warm nose is eroding the CAD around RDU.


Sent from my iPhone using Tapatalk

 

[Webberweather53]

We had a lot more cold in the source region in 2014 correct?

Yeah we definitely had more low-level cold air and deeper snow cover to the north to work w/ prior to the Feb 2014 event which produced most of its ZR south of I-20 in SC & GA. A similar synoptic setup but warmer low-level thermals could spell trouble for more climatologically favored areas NW of there like CLT, GSP, RDU, etc imo.

 

[SD]

I'm guessing the warm nose is eroding the CAD around RDU.


Sent from my iPhone using Tapatalk

It only gets the dew at RDU down to 27. We spend a lot of hours at 34/33 and 35/34

 

[Webberweather53]

I'm guessing the warm nose is eroding the CAD around RDU.


Sent from my iPhone using Tapatalk

The warm nose itself doesn't erode CAD, precipitation fluxing sensible heat from the warm nose to the low-level cold dome, cold air advection in the mid-levels, solar insolation, etc are what actually erode a CAD. Contrary to popular belief, a mid-level warm nose actually makes CAD stronger by strengthening the inversion at the top of the CAD dome and locking the low-level cold air in place and preventing it from mixing with the warmer air aloft. Without mid-level warm advection that accompanies CAD, there arguably wouldn't be CAD in the first place.

 

[Myfrotho704_]

 

[Webberweather53]

We've trended towards a stronger wave pattern, more confluence, and more cold advection over New England & SE Canada prior to this storm on Wednesday, which strengthens the parent sfc high over the Lakes & NE US. Our shortwave over the southern plains is hanging back a bit longer in new model runs, allowing the cold air to our N-NE to build in a bit more prior to the onset of the storm, pretty close to optimal timing overall in a general sense. Looks like a major ice storm is definitely on the table unfortunately.

 

[SD]

View attachment 57239View attachment 57234View attachment 57236

Any of them icon dew point maps available

 

[Myfrotho704_]

Any of them icon dew point maps available

I really wish I did have them but weathermodels doesn’t have it (which I have) I think weatherbell does, sorry man

 

[SD]

Icon continues to slowly dip south in the NE

 

[Webberweather53]

Icon coView attachment 57241ntinues to slowly dip south in the NE

This trend needs to stop real soon or even down here in Fayetteville, I'm going to be sweating bullets over trying to avoid major ZR.

 

[Myfrotho704_]

This trend needs to stop real soon or even down here in Fayetteville, I'm going to be sweating bullets over trying to avoid major ZR.

If it continues to trend more that way, you think IP could find its way into the mix more ? Especially for areas further NW

 

[J.C.]

If the Monday storm were to drop a decent snow pack on the mid Atlantic, would that help temps slightly? I know it doesn't appear to drop a whole at this point.

 

[Webberweather53]

If it continues to trend more that way, you think IP could find its way into the mix more ? Especially for areas further NW

Yeah especially for the Triad and points NW the cooling trend will be good to see as this would end up being more of a IP fest &/or potentially a brief thump of snow at the onset. Once you get down to about the CLT-RDU corridor or so & pts SE towards my neck of the woods & NE GA, you definitely don't wanna see this trend continue much longer or we could have big problems.