January 12th-13th event

[wxduncan]

1 minute ago, wncsnow said:

12Z NAM says otherwise. Most ice it has shown all storm long. 

Was about to say the same thing also the hires NAM does to.

0.33-0.89(Isolated higher pockets also) around Hickory and west. Might not be snow but that's some serious ICE. Even the morning GFS run increased ice totals for my parts to above 0.25-0.48.

[HurricaneTracker]

1 minute ago, wncsnow said:

12Z NAM says otherwise. Most ice it has shown all storm long. 

I know...I looked at it.  But my feel is that the NAM is wrong.  It’s far too cold.  Look at initialization 2m temps this morning versus observed. It was too cold by 2-3 degrees most places. Every CAD event we have had here since November (along with RGEM) has been too cold and showing nasty ice storms when they have yet to verify.  I think this event is no different. Go with the GFS if you want a solution that’s closer to reality.

[wncsnow]

4 minutes ago, HurricaneTracker said:

I know...I looked at it.  But my feel is that the NAM is wrong.  It’s far too cold.  Look at initialization 2m temps this morning versus observed. It was too cold by 2-3 degrees most places. Every CAD event we have had here since November (along with RGEM) has been too cold and showing nasty ice storms when they have yet to verify.  I think this event is no different. Go with the GFS if you want a solution that’s closer to reality.

Well the GFS and especially GFSV3 is getting icier for piedmont regions in recent runs

[McDowell_Weather]

Fv3 has honestly been steady as she goes for a while not surprised it done good with the December storm too for my area.

[DC2Winston]

Nothing hit the ground in Winston under the Radar returns past hour. Virga party. 

[Blue_Ridge_Escarpment]

Sleeting in Clemson 

[Blue_Ridge_Escarpment]

1 hour ago, HurricaneTracker said:

I know...I looked at it.  But my feel is that the NAM is wrong.  It’s far too cold.  Look at initialization 2m temps this morning versus observed. It was too cold by 2-3 degrees most places. Every CAD event we have had here since November (along with RGEM) has been too cold and showing nasty ice storms when they have yet to verify.  I think this event is no different. Go with the GFS if you want a solution that’s closer to reality.

HT you’re running out of models to hang non wintry solutions on. GFS finally getting a clue at the 11th hour. Gfs is horrendous with CAD events. 

[Lookout]

1 hour ago, HurricaneTracker said:

I know...I looked at it.  But my feel is that the NAM is wrong.  It’s far too cold.  Look at initialization 2m temps this morning versus observed. It was too cold by 2-3 degrees most places. Every CAD event we have had here since November (along with RGEM) has been too cold and showing nasty ice storms when they have yet to verify.  I think this event is no different. Go with the GFS if you want a solution that’s closer to reality.

I think this is the first time  i have ever heard or seen someone argue for the gfs in a cad event. If you are in zone of cad real estate in north carolina,  you are making a terrible mistake hanging your hat on the gfs. 

At any rate, the nam is also too warm...in some cases by 5 to 7 degrees with dewpoints. For example, the nam..including the 3km, has dewpoints of around 28/29 in the upstate..when in reality they are in the 20 to 22 range. Looks like it's off by around 5 degrees in north carolina.

On average, when there is actually some respectable dewpoint depressions and evaporation to be had...which the event in december did not have at all, , the average error rate is  1 to 3 degrees too warm after saturation...with the old gfs being upwards of 3 to 5 degrees.,especially on the edges. 

[MyBookMonkey]

20 minutes ago, Lookout said:

I think this is the first time  i have ever heard or seen someone argue for the gfs in a cad event. If you are in zone of cad real estate in north carolina,  you are making a terrible mistake hanging your hat on the gfs. 

At any rate, the nam is also too warm...in some cases by 5 to 7 degrees with dewpoints. For example, the nam..including the 3km, has dewpoints of around 28/29 in the upstate..when in reality they are in the 20 to 22 range. Looks like it's off by around 5 degrees in north carolina.

On average, when there is actually some respectable dewpoint depressions and evaporation to be had...which the event in december did not have at all, , the average error rate is  1 to 3 degrees too warm after saturation...with the old gfs being upwards of 3 to 5 degrees.,especially on the edges. 

Whatcha thinking for your area?

[Lookout]

2 hours ago, CamWX said:

Short burst of sleet all the way down here. 38.2/26. Sadly all we'll probably get.

Had a little a few minutes ago too. Looks like game over for south of 85 this go around.  I'm not sure if the nam's error on surface dewpoints also extends into the low levels but the past few runs warmed the 950mb to 975mb also and the combo of that, the worst possible timing of precip, and  current temps, it's hard to see anywhere south of gainesville to hartwell/south of 85 getting much.  It will be colder than the models are showing ...but probably one of those 32.5  degree  deals. Still think gainesville, cornella, toccoa, etc get some. Anyone with any elevation should do  well. 

i sure hope this pattern change up ahead comes to pass. These marginal events that end up on the plus side of 32 get old real quick. 

[Lookout]

5 minutes ago, MyBookMonkey said:

Whatcha thinking for your area?

As mentioned above, probably bottoming out around 32.5...wouldn't be surprised to see 32.1   to  make it especially annoying lol 

[tarheelwx]

I have a request, and feel free to set me straight if I'm wrong.  Stating that dewpoints are running lower than the models are showing without stating the humidity really doesn't tell us anything.  Honestly, what we really need to know is wet bulb temp as it factors in evaporational cooling and the relationship between dewpoint and temps.  If the wet bulbs are indeed running several degrees lower than models are showing, then that is really significant.  However, a dewpoint of 22 with a temp of 40 is really about the same as dewpoint of 28 and a temp or 36, or dewpoint of 34 and temp of 34 (100% rh).  Just stating the dewpoint isn't providing all of the info needed to definitively state that the models are off on the surface temps. (my rule of thumb to figure out how far the temp will fall once precip saturates the atmosphere is to take the difference between temp and dewpoint, divide it by 3, and subtract that number from the actual temp - it is usually really close)

Thanks,

TW

[MyBookMonkey]

29 minutes ago, Lookout said:

Had a little a few minutes ago too. Looks like game over for south of 85 this go around.  I'm not sure if the nam's error on surface dewpoints also extends into the low levels but the past few runs warmed the 950mb to 975mb also and the combo of that, the worst possible timing of precip, and  current temps, it's hard to see anywhere south of gainesville to hartwell/south of 85 getting much.  It will be colder than the models are showing ...but probably one of those 32.5  degree  deals. Still think gainesville, cornella, toccoa, etc get some. Anyone with any elevation should do  well. 

i sure hope this pattern change up ahead comes to pass. These marginal events that end up on the plus side of 32 get old real quick. 

Hmm do you think this could be like the feb 2015 event? I remember the nws had to play catch up hard on that one

[HurricaneTracker]

46 minutes ago, Lookout said:

I think this is the first time  i have ever heard or seen someone argue for the gfs in a cad event. If you are in zone of cad real estate in north carolina,  you are making a terrible mistake hanging your hat on the gfs. 

At any rate, the nam is also too warm...in some cases by 5 to 7 degrees with dewpoints. For example, the nam..including the 3km, has dewpoints of around 28/29 in the upstate..when in reality they are in the 20 to 22 range. Looks like it's off by around 5 degrees in north carolina.

On average, when there is actually some respectable dewpoint depressions and evaporation to be had...which the event in december did not have at all, , the average error rate is  1 to 3 degrees too warm after saturation...with the old gfs being upwards of 3 to 5 degrees.,especially on the edges. 

Terrible mistake?  Hmm. I call it forecaster intuition. To be fair, GFS still shows ice accretions along and north of AVL.  I think this is far more realistic than the NAM which has ice accumulations over 0.75" across a broad swath of the central and northern foothills/mountains. Yes dewpoints are dry and yes there will be wetbulbing.  But NAM and RGEM are notorious at overdoing ice accumulations.  GFS is still a respectable event.  Somebody is going to get a cold rain inside the warning area.

To that end, even the latest HRRR is more GFS-like than the overly icy NAM.  Just saying my experience in CAD ice storm events specifically is that NAM overcools the surface (but does capture warm nose aloft), while GFS is more realistic at the surface but can underdo the warm nose.  

[GunBlade]

My intuition from living here my whole life is that whatever model doesn’t show wintry precip for my area will be the one that’s correct. Every event has been so marginal for years that I’ve forgotten what it’s like to just get a good snow with no sleet or ZR mixed in.  And I’ve had more cold rains at 33 than I care to count but looks like we can tally another one up after this storm. 

[Lookout]

39 minutes ago, tarheelwx said:

I have a request, and feel free to set me straight if I'm wrong.  Stating that dewpoints are running lower than the models are showing without stating the humidity really doesn't tell us anything.  Honestly, what we really need to know is wet bulb temp as it factors in evaporational cooling and the relationship between dewpoint and temps.  If the wet bulbs are indeed running several degrees lower than models are showing, then that is really significant.  However, a dewpoint of 22 with a temp of 40 is really about the same as dewpoint of 28 and a temp or 36, or dewpoint of 34 and temp of 34 (100% rh).  Just stating the dewpoint isn't providing all of the info needed to definitively state that the models are off on the surface temps. (my rule of thumb to figure out how far the temp will fall once precip saturates the atmosphere is to take the difference between temp and dewpoint, divide it by 3, and subtract that number from the actual temp - it is usually really close)

Thanks,

TW

This is true but my main point responding to his premise that the nam was running too cold when in reality the nam's dewpoints are also too high so it's not running warm at all. In fact, wetbulbs are in fact lower than the nam is showing.  For example, spartanburg memorial and hickory  are  37 over 19...nam has it 38  over 27 right now and 38/25 respectfully.   I use the same general rule of thumb for quick calculations but  There a number of wetbulb calculators there like this one. 

http://www.ringbell.co.uk/info/humid.htm

 

27 minutes ago, HurricaneTracker said:

Terrible mistake?  Hmm. I call it forecaster intuition. To be fair, GFS still shows ice accretions along and north of AVL.  I think this is far more realistic than the NAM which has ice accumulations over 0.75" across a broad swath of the central and northern foothills/mountains. Yes dewpoints are dry and yes there will be wetbulbing.  But NAM and RGEM are notorious at overdoing ice accumulations.  GFS is still a respectable event.  Somebody is going to get a cold rain inside the warning area.

To that end, even the latest HRRR is more GFS-like than the overly icy NAM.  Just saying my experience in CAD ice storm events specifically is that NAM overcools the surface (but does capture warm nose aloft), while GFS is more realistic at the surface but can underdo the warm nose.  

It's your choice to lean on it but   very rarely does the gfs not be a few degrees too warm with surface temps when there is dry air in place.  I'd  be cautious using  the hrrr in these setups too....it often  has a warm  bias at the surface..especially in the longer range. It's been downright awful at times with dewpoints the past few days here . Indeed, looking at the 10z run, it's way way off in most places. low 40s in nc foothills over mid 20 dewpoints..when in reality it's upper 30s and upper teens/low 20s.  The profiles  at 900mb to 975mb over nc looks very favorable for cooling too, including the gfs.  Also, those maps are not accretion maps...those are just precip amounts that fall with temps at or below freezing...which is often much less than those maps show. 

I can't say the nam is too cold very often in cad down this way. It was about 1 degree too cold in december but again that was a totally different, and rather unusual cad situation where the caa commenced long after it started raining...and we all know moisture chasing cold doesn't normally work out around here

We'll see i guess but i'd wager on quite a lot of ice in the areas being shown  in north carolina...although as cold as 900mb to surface temps are, sleet could save the day in some areas, especially foothills. 

[calculus1]

30 minutes ago, Lookout said:

This is true but my main point responding to his premise that the nam was running too cold when in reality the nam's dewpoints are also too high so it's not running warm at all. In fact, wetbulbs are in fact lower than the nam is showing.  For example, spartanburg memorial and hickory  are  37 over 19...nam has it 38  over 27 right now and 38/25 respectfully.   I use the same general rule of thumb for quick calculations but  There a number of wetbulb calculators there like this one. 

http://www.ringbell.co.uk/info/humid.htm

For verification purposes, @Lookout, my Davis Vantage Vue is currently measuring 38.2 over 24 right now IMBY.  (I'm less than five miles away from the Hickory airport.)  Using your linked calculator, with my current atmospheric pressure reading of 1031.2 mb, I get a wet-bulb temperature of 33 degrees.  Unfortunately, that's only good enough for a nice cold rain, despite the Winter Storm Warning hoisted for my county that mentions snow/sleet accumulations up to 2 inches and ice accretion between 0.1 and 0.4 inch.  I'm hoping the CAD will kick in stronger this afternoon and evening to lower my wet-bulb temperature, but right now it's a "No go" for ice.

[Blue_Ridge_Escarpment]

Euro playing catch up. 3x as much ice as 0Z run 

[avianman]

2 minutes ago, calculus1 said:

For verification purposes, @Lookout, my Davis Vantage Vue is currently measuring 38.2 over 24 right now IMBY.  (I'm less than five miles away from the Hickory airport.)  Using your linked calculator, with my current atmospheric pressure reading of 1031.2 mb, I get a wet-bulb temperature of 33 degrees.  Unfortunately, that's only good enough for a nice cold rain, despite the Winter Storm Warning hoisted for my county that mentions snow/sleet accumulations up to 2 inches and ice accretion between 0.1 and 0.4 inch.  I'm hoping the CAD will kick in stronger this afternoon and evening to lower my wet-bulb temperature, but right now it's a "No go" for ice.

Just 10 miles to your NE at Riverbend Park, we are at 36.6 and DP of 22. Wetbulb at 31.

[Lookout]

54 minutes ago, GunBlade said:

My intuition from living here my whole life is that whatever model doesn’t show wintry precip for my area will be the one that’s correct. Every event has been so marginal for years that I’ve forgotten what it’s like to just get a good snow with no sleet or ZR mixed in.  And I’ve had more cold rains at 33 than I care to count but looks like we can tally another one up after this storm. 

Isn't that the truth. I usually have to travel to escape the 33 degree rain BS...especially these past few years.  Folks up north don't realize how lucky they are that temp issues are often so much clearer than down here and don't normally come down to one degree so often. What i wouldn't give for a clear cut cold enough storm where the only question is how much of whatever wintery is falling instead of this dissecting temp/wetbulb nonsense.   It seems like it's been a long time too since we had a storm over perform by a lot...especially freezing rain...but that's because  models are quite a bit better than they used to be  so any real big surprises are rare these days. 

15 minutes ago, calculus1 said:

For verification purposes, @Lookout, my Davis Vantage Vue is currently measuring 38.2 over 24 right now IMBY.  (I'm less than five miles away from the Hickory airport.)  Using your linked calculator, with my current atmospheric pressure reading of 1031.2 mb, I get a wet-bulb temperature of 33 degrees.  Unfortunately, that's only good enough for a nice cold rain, despite the Winter Storm Warning hoisted for my county that mentions snow/sleet accumulations up to 2 inches and ice accretion between 0.1 and 0.4 inch.  I'm hoping the CAD will kick in stronger this afternoon and evening to lower my wet-bulb temperature, but right now it's a "No go" for ice.

Interesting....looking at observations though, all the nws sites and many of the others in the western piedmont/foothills are showing dewpoints of 18 to 22. maybe you are in a wet spot lol 

As for your neck of the woods though, it's more than just about the surface temps/wetbulbs ....the air right off the ground all the way up to at least 925mb to 900mb   will be very cold and is every bit as important as the current surface observations. No matter which model you look at, 925mb to 975mb temps will be well down into the 20s over your area.  It's a crucial piece to the puzzle....as you can have subfreezing wetbulbs but if the surface pool isn't deep enough, it doesn't matter and you end up with not much of anything. In this case though  There really shouldn't be any problem getting below freezing up your way. 

 

[calculus1]

2 minutes ago, Lookout said:

Interesting....looking at observations though, all the nws sites and many of the others in the western piedmont/foothills are showing dewpoints of 18 to 22. maybe you are in a wet spot lol 

As for your neck of the woods though, it's more than just about the surface temps/wetbulbs ....the air right off the ground all the way up to 900 or 925mb will be very cold and is every bit as important as the current surface observations. No matter which model you look at, 925mb to 975mb temps will be well down into the 20s over your area.  It's a crucial piece to the puzzle....as you can have subfreezing wetbulbs but if the surface pool isn't deep enough, it doesn't matter and you end up with not much of anything. In this case though  There really shouldn't be any problem getting below freezing up your way.

Ha!  That may be the case.  Who knows?  My wet-bulb is down to 32.8 now, so it is slightly falling.  I checked the recent airport conditions, and they wet-bulb to 31.8 right now.  Anyway, I hope you are right about the last bolded statement in your quote.  Time will tell...

[packfan98]

17 minutes ago, Blue_Ridge_Escarpment said:

Euro playing catch up. 3x as much ice as 0Z run 

It really ramped up the precip totals for the mountains and foothills. Now showing over one inch totals. 

[calculus1]

6 minutes ago, packfan98 said:

It really ramped up the precip totals for the mountains and foothills. Now showing over one inch totals. 

[CAD_Wedge_NC]

2 minutes ago, calculus1 said:

What do the temp profiles look like on the Euro?

[calculus1]

4 minutes ago, CAD_Wedge_NC said:

What do the temp profiles look like on the Euro?

Warmer than the NAM.  Hickory would get a pretty cold rain, but very little ice if the Euro is correct.  Just to our west would get lots of ZR though.

[BIG FROSTY]

2 minutes ago, calculus1 said:

Warmer than the NAM.  Hickory would get a pretty cold rain, but very little ice if the Euro is correct.  Just to our west would get lots of ZR though.

How about up this way on temps?

 

[calculus1]

From NWS GSP:

[calculus1]

4 minutes ago, BIG FROSTY said:

How about up this way on temps?

 

This panel shows the furthest reach of the freezing precipitation types of the most recent Euro run:

[CAD_Wedge_NC]

1 minute ago, calculus1 said:

From NWS GSP:

Looks like a quarter of an inch of ice in our neck of the woods. I am just to your south.

[calculus1]

1 minute ago, CAD_Wedge_NC said:

Looks like a quarter of an inch of ice in our neck of the woods. I am just to your south.

Yes, which I find very interesting.  The relative max with ZR is usually right up against the Blue Ridge, but this forecast is showing our area getting more.  I would have to guess that would be due to a forecast of more sleet falling closer to the Blue Ridge and less here.