CAD storms thread.

[FallsLake]

NAM simulated radar at hour 24:

[HKY18]

12z nam looks pretty juicy compare to previous runs

[NCCatawba]

12z NAM is weeeeeet.

 

That is very strong isentropic lift over the CAD. Now we just need a consecutive NAM model that will agree...because we saw this same issue yesterday.

[Cold Rain]

Why in the world does the Nam change so much from run to run? It's dry. It's wet. It's dry again. No wait, it's wet again. Is this type of event conducive to such model mayhem or is the Nam just horrible with its QPF?

[Blue_Ridge_Escarpment]

I could be wrong, but it appears the wedge held on longer on this run of the NAM, thoughts?

[Buddy1987]

^{NAM equals crippling ice storm for VA. If that comes to fruition people are in big trouble.}

[NCCatawba]

Why in the world does the Nam change so much from run to run? It's dry. It's wet. It's dry again. No wait, it's wet again. Is this type of event conducive to such model mayhem or is the Nam just horrible with its QPF?

 

Robert:

The big unknown for southwest VA and northern , nw NC is the amount of moisture and where that jet axis aloft lines up because sometimes the models miss that , and in this case a few miles of error will have a huge impact on the amount of freezing rain coming down. I hedged more north, not south, but I'll monitor this.

[Cold Rain]

Robert:

The big unknown for southwest VA and northern , nw NC is the amount of moisture and where that jet axis aloft lines up because sometimes the models miss that , and in this case a few miles of error will have a huge impact on the amount of freezing rain coming down. I hedged more north, not south, but I'll monitor this.

Hmmm. Interesting, thanks. We'll wait for the others now.

[BIG FROSTY]

can someone give me the best guess on start time of precip tonight or tomorrow morning? I'm going to leave Pigeon forge tonight sometime and go home, I want to beat the precip to fancy gap mountain!!! Lol

[tarheelwx]

can someone give me the best guess on start time of precip tonight or tomorrow morning? I'm going to leave Pigeon forge tonight sometime and go home, I want to beat the precip to fancy gap mountain!!! Lol

Looks like between 12 and 3am.

TW

[BIG FROSTY]

Robert, still thinks it will mount to pretty much nothing in North Carolina in my area? it's mostly a central and northern Virginia storm!!! Temps just marginal in my area and very little moisture... I have to say robert has always been the best forecaster on these CAD events. We'll soon find out who will be right.

[BIG FROSTY]

Looks like between 12 and 3am.

TW

appreciate that!

[tarheelwx]

As far as the severity of the ice, there is a huge difference between .5" qpf at 32 degrees vs. 30 degrees.  For places that only get down to 32 degrees, I doubt it will amount to much, especially considering the very warm 850's.  While so many are focusing on how much precip falls, I think the 30 degree mark is almost as important. 

TW

[tarheelwx]

Just looked at the NAM reading for GSO and it now only had the temp down to 32 for just a couple of hours.  I expected it to be just a bit cooler, not warmer.  Funny in that it also put out a period of thundersleet.  Here's a link.  If you want to find another location, just change "gso" to another location.  Roanoke gets hit pretty hard this time.

http://68.226.77.253/text/NAMSFC/NAM_kgso.txt

TW

[NCCatawba]

As far as the severity of the ice, there is a huge difference between .5" qpf at 32 degrees vs. 30 degrees.  For places that only get down to 32 degrees, I doubt it will amount to much, especially considering the very warm 850's.  While so many are focusing on how much precip falls, I think the 30 degree mark is almost as important. 

TW

 

There is but the placement of ice is another factor. I usually see no difference between 32 vs 30 since when we are talking trees and powerlines. If we were talking about cars, roadways, grassy areas, etc. then the few degrees matter more imo. This has the blue ridge parkway written all over it on the NAM.

[tarheelwx]

Even at 30 degrees, its difficult to get ice on the roads.  Much of it would be dependent on ground temps prior to the storm.  As for the trees, I think it is even difficult at 32 degrees.  Where it is possible is when the precip is light.  If you get a fairly moderate and "warm" rain, it is difficult even in the trees.  Not impossible and there would be some, but just not a whole lot. 

TW

[CAD_Wedge_NC]

It will be interesting to watch the temp post 3pm Sunday. Boone will be 10 degrees warmer compared to Greensboro going into the late evening or nighttime. From ice storm to waking up to it being mild Monday morning for Boone. 

 

Here is the very latest from Ray's Weather.

 

 

Do you have permission from Ray Weather to post that image? You cannot post anything from his site without permission.....period...... Understand?

 

 

[tarheelwx]

A note about temps in the NC cad area.  Its pretty common for the triad over to the n foothills to have about the same temps as roanoke, lynchburg, etc.  With ne winds until Monday morning, I think the temps will get just below freezing, maybe 30-31.

TW

[BIG FROSTY]

A note about temps in the NC cad area. Its pretty common for the triad over to the n foothills to have about the same temps as roanoke, lynchburg, etc. With ne winds until Monday morning, I think the temps will get just below freezing, maybe 30-31.

TW

To really get in on the ice action, I think we need it ,30 or lower. Which probably not going to happen. Robert says 31 or 32 my area!

[tarheelwx]

To really get in on the ice action, I think we need it ,30 or lower. Which probably not going to happen. Robert says 31 or 32 my area!

I agree that is likely.  However, you and I both know how many times it has ended up a couple of degrees colder and 6-9 hours longer.  Most of those times, the hp has locked in and come in just a bit stronger.  It seems the hp is not coming in any stronger on recent model runs.  Anyway, will be fun to watch.

TW

[NCCatawba]

The nam is just insane. Ice Storm Warning criteria would be obtained through all the way to hour 39 shown here in the darker blue esp. (Blue Ridge Parkway).

 

[NEGa]

To really get in on the ice action, I think we need it ,30 or lower. Which probably not going to happen. Robert says 31 or 32 my area!

 while yes freezing rain can fall at 32, i lean towards the 30-or-lower temps for a real ice storm, so to speak.  30 or 31 will give a nice glaze on the trees, decks, cars, etc.  to get a good solid icing event around here, at least, temps generally are below 30.  its not as common to have the roads iced over in n ga, that usually takes a period of cold temps prior to the event (not saying it cant happen if the temp drops to the mid 20s, but its just not that common imby). 

 

for ga, at east, 31 or 32 is such a tenuous temperature it doesnt take much to go above/below during the event, esp during periods of heavier precip, which unfortunately limits the accretion

 

edited to add:

 

 

 

The nam is just insane. Ice Storm Warning criteria would be obtained through all the way to hour 39 shown here in the darker blue esp. (Blue Ridge Parkway).

 

 

maybe its just me (still drinking coffee) and/or been so long since we have had these semi regular cad events modeled, but this one seems a little displaced to the west. usually the higher elevations warm up and its the lower valleys that have the cold air settle in them.   i recall them being  a little to the east in the areas that are adjacent to the mtns, not in the western nc mtns per se

[griteater]

Just looked at the NAM reading for GSO and it now only had the temp down to 32 for just a couple of hours.  I expected it to be just a bit cooler, not warmer.  Funny in that it also put out a period of thundersleet.  Here's a link.  If you want to find another location, just change "gso" to another location.  Roanoke gets hit pretty hard this time.

http://68.226.77.253/text/NAMSFC/NAM_kgso.txt

TW

 

Depends on which model is to be believed.  The GFS has GSO at 31 degrees for the bulk of the day tomorrow, and not fully saturated with wet bulbs a degree or 2 colder.

[Bsudweather]

while yes freezing rain can fall at 32, i lean towards the 30-or-lower temps for a real ice storm, so to speak. 30 or 31 will give a nice glaze on the trees, decks, cars, etc. to get a good solid icing event around here, at least, temps generally are below 30. its not as common to have the roads iced over in n ga, that usually takes a period of cold temps prior to the event (not saying it cant happen if the temp drops to the mid 20s, but its just not that common imby).

for ga, at east, 31 or 32 is such a tenuous temperature it doesnt take much to go above/below during the event, esp during periods of heavier precip, which unfortunately limits the accretion

edited to add:

maybe its just me (still drinking coffee) and/or been so long since we have had these semi regular cad events modeled, but this one seems a little displaced to the west. usually the higher elevations warm up and its the lower valleys that have the cold air settle in them. i recall them being a little to the east in the areas that are adjacent to the mtns, not in the western nc mtns per se

I will be really surprised if temps drop below 36 here. But CADs usually always has tricks in the hat if there are moisture around.

[Disc]

It appears the 12z GFS has the heavy precip similar to where the NAM had it.

[swva]

^{NAM equals crippling ice storm for VA. If that comes to fruition people are in big trouble.}

Buddy/Disc - Agree... This run is a little warmer for our area but still stays below freezing for 18-24 hours.  If NAM is right, get ready for power outages.  What a drastic shift from the last several runs.  Let's see if GFS gets on board.

[griteater]

12z GFS is still driving the wedge in a bit colder than the NAM

[Buddy1987]

It appears the 12z GFS has the heavy precip similar to where the NAM had it.

 

Buddy/Disc - Agree... This run is a little warmer for our area but still stays below freezing for 18-24 hours.  If NAM is right, get ready for power outages.  What a drastic shift from the last several runs.  Let's see if GFS gets on board.

Guys if I were NWS and to an extent the Euro agrees on what the Nam and GFS are showing, even tho its starting to be at the point where the Euro's range is not as useful, I would definitely put out an Ice Storm Warning and put the emphasis on what kind of impact this would have to the area as a Winter Storm Warning is used more for snow and sleet purposes and in my mind wouldnt grab the communities attention as much. That amount of qpf, what it would do to the area if it switched over to freezing rain rather quickly would be a severe event to say the least.

[NCCatawba]

Disagreement in the cold placement. NAM prefers the freezing temps getting locked along the blue ridge while the GFS prefers it getting locked near Reidsville, NC. 

[Blue_Ridge_Escarpment]

Appears to be two different thoughts right now.  The NAM wants to bring the wedge in right down the eastern blue ridge and hold it there for a good while, the GFS wants to bring in a more wider wedge mostly confined to central NC.  Don't know which is right.