Feb. 18-20, 2012 Disco/Analysis

[burgertime]

Re-read my post i never said per Euro, I am thinking on more of a model consensus. The Euro does indeed show some nice accums for the I-40 corridor.

BTW looking at the GSP AFD and the point forecasts for even the mtns,, imagine if the EURO verified it is 360 different from their current forecast and would catch many off guard

Fair enough. Must have read too quickly.

[RaleighWx]

Getting run to run, looked at the euro snowfall forecast from a vendor site. Like like most of the northern half of NC is in the 4-8 inches. From HKY to GSO to RDU to RWI, 2-4 is south of that southern foothills to near CLT to Southern Pines to Greenville.

Big change for sure.

[strongwxnc]

Big change for sure Allan...

Thanks for posting this info.

Getting run to run, looked at the euro snowfall forecast from a vendor site. Like like most of the northern half of NC is in the 4-8 inches. From HKY to GSO to RDU to RWI, 2-4 is south of that southern foothills to near CLT to Southern Pines to Greenville.

Big change for sure.

[Brick Tamland]

Getting run to run, looked at the euro snowfall forecast from a vendor site. Like like most of the northern half of NC is in the 4-8 inches. From HKY to GSO to RDU to RWI, 2-4 is south of that southern foothills to near CLT to Southern Pines to Greenville.

Big change for sure.

Seems like the closer we get, the more south the big snow comes. This is an amazing turnaround!

[SN_Lover]

Not buying into the models right now. If the movement is from West to East, with regards to precio, then the Apps will retard precipitation and temperatures to the East. The downsloping will kill chances of snow for the foothills and the western Piedmont. i would be optimistic if i lived in the eastern part of the Carolina's though...to see snow falling.

[Tullioz]

If you look at the video I posted we received a dusting with just moderate off and on snow in March at 33 when it was around 55 for the week before. Now the roads might not take to it to well but if we got .3 or .4 of heavy rates how would it not accumulate? I just don't get that logic. Just verbatim on the Euro, how would you not get accumulations outside of the roads in say GSO or Winston?

There are several reasons why there will be no accumulations in the Piedmont. The year that you took the video was a more normal temperature wise and I am sure soil temperatures were not as warm as they are at this point. (The map that was posted earlier shows this.) Like I mentioned in my earlier post we should all be thinking of this as a March 20th storm rather than a february 20th storm. That way expectations would be more realistic. As for the other factors against accumulating snow, First there is no cold air in place, therefore we have to wait on a changeover which will waist a lot of the precipitation, as a good portion will fall as rain. Second, The heaviest precipitation falls during the day so even falling as snow you will be fighting the effects of the sun. Third, the storm is so progressive it is in and out pretty fast. 8 to 12 hours as it appears on the Euro. Figure in a good portion initially falling as rain and you are left with just a few hours of snow. Even with heavy snow rates it will not last long enough for significant accumulations. The best anyone in the Piedmont can hope for at this point is a slushy accumulation on grassy surfaces. (less than 1") and this is based on the Euro only. The GFS and NAM look even worse.

[WeatherNC]

Getting run to run, looked at the euro snowfall forecast from a vendor site. Like like most of the northern half of NC is in the 4-8 inches. From HKY to GSO to RDU to RWI, 2-4 is south of that southern foothills to near CLT to Southern Pines to Greenville.

Big change for sure.

So are you buying it at this point, even half that would be on the far edge of the envelope... I doubt any WFO will latch on at this point and rightfully so until there is better agreement, but you cannot totally discount the Euro at this stage, it handled our non event here last week much better than the americans at this range, NAM/GFS were pretty consistent on 1/2"+ 24-72hrs out, EC was consistent on a trace event, ended up with a couple hundredths... Last year I think we tried to buck it a couple times pinning hopes on clippers that the NAM/GFS showed putting down 1/4-1/2", Euro was dry, and so was the clipper when all was said and done. Cautiously optimistic should be the mood until things come better into focus, continuing trend back towards what we saw last Fri/Sat, funny!

[packbacker]

There are several reasons why there will be no accumulations in the Piedmont. The year that you took the video was a more normal temperature wise and I am sure soil temperatures were not as warm as they are at this point. (The map that was posted earlier shows this.) Like I mentioned in my earlier post we should all be thinking of this as a March 20th storm rather than a february 20th storm. That way expectations would be more realistic. As for the other factors against accumulating snow, First there is no cold air in place, therefore we have to wait on a changeover which will waist a lot of the precipitation, as a good portion will fall as rain. Second, The heaviest precipitation falls during the day so even falling as snow you will be fighting the effects of the sun. Third, the storm is so progressive it is in and out pretty fast. 8 to 12 hours as it appears on the Euro. Figure in a good portion initially falling as rain and you are left with just a few hours of snow. Even with heavy snow rates it will not last long enough for significant accumulations. The best anyone in the Piedmont can hope for at this point is a slushy accumulation on grassy surfaces. (less than 1") and this is based on the Euro only. The GFS and NAM look even worse.

Your right...the cold is marginal, we are relying solely on timing and track, long odds for central NC to get accumulating snowfall, but northern counties can get 1-2" on grass.

[Tullioz]

Your right...the cold is marginal, we are relying solely on timing and track, long odds for central NC to get accumulating snowfall, but northern counties can get 1-2" on grass.

Based on this run of the Euro alone I doubt anyone outside of the mountains gets that much. It even takes Virginia out of the game. The most likely places to see 1 to 2 inches would be the extreme NE parts of NC mainly because of the moisture hanging on a little longer and the timing which would be after sunset.

[GaWx]

Per 12Z 2/17 Doc snow output maps: (interpolate for other cities)

1) NC: the Triad, the Triangle and HKY get ~5", Asheville ~4", Charlotte ~2".

2) TN: Johnson City ~6", Knoxville ~3".

[Dunkman]

I just want to reply that the euro is the most accurate model at all time ranges. I'm not buying the huge NC snow either but to say it is bad in the short range is just wrong.

[WeatherNC]

12z GFS mems @ 60 & 66

Looking at the sn-fall maps, major difference between the euro is taking a heavy band into central, euro dried out quickly north of a line from LYH-RIC, consensus from these members does not support that.

[valkhorn]

I hate to be in disagreement with some well known mets, but i do not see a significant snowfall in east or northeast TN. I agree that 1 inch at KTRI is possible, but not probable. There is a distinct warm nose that is depicted on the modeling and that warm nose absolutely loves to hang on. I don't see any reason to be against it. For TN my call is:

Nashville - inch or less

Knoxville - 1/2 inch or less

Cookeville and Crossville - 2-4 inches

Tricities - inch or less

Chattanooga - 0

East TN mountains - 1-2, another 1 possible in backlash/upslope

Big winners west of the apps - southeastern/eastern KY, southwest Virginia (4-6 inches, locally 8)

As for NC, I have no idea

I think some spots in eastern KY or WV will approach or exceed 12". It looks like it'll be a narrow but heavy band just north of the TN/KY border and across the WV/VA/KY tri-state area.

As far as the NW flow upslope, I think the highest elevations could be in like flint after it is over. The last arctic front put about 8" on places above 6000' in the Smokys last weekend (I was there to see it) so I think 2-4" + is possible up there when the NW winds kick in.

[burgertime]

There are several reasons why there will be no accumulations in the Piedmont. The year that you took the video was a more normal temperature wise and I am sure soil temperatures were not as warm as they are at this point. (The map that was posted earlier shows this.) Like I mentioned in my earlier post we should all be thinking of this as a March 20th storm rather than a february 20th storm. That way expectations would be more realistic. As for the other factors against accumulating snow, First there is no cold air in place, therefore we have to wait on a changeover which will waist a lot of the precipitation, as a good portion will fall as rain. Second, The heaviest precipitation falls during the day so even falling as snow you will be fighting the effects of the sun. Third, the storm is so progressive it is in and out pretty fast. 8 to 12 hours as it appears on the Euro. Figure in a good portion initially falling as rain and you are left with just a few hours of snow. Even with heavy snow rates it will not last long enough for significant accumulations. The best anyone in the Piedmont can hope for at this point is a slushy accumulation on grassy surfaces. (less than 1") and this is based on the Euro only. The GFS and NAM look even worse.

Here is the write up for that event:

http://www4.ncsu.edu...cases/20100302/

A few highlights:

..Uncertainty in the amount of forecast precipitation along with surface temperatures at or just above freezing, warmer soil temperatures then typically associated with accumulating snow, and the late season nature of the storm made snow accumulation forecasts very difficult...

][/b]A relatively warm boundary layer with temperatures above freezing extended from the surface up to a few thousand feet when the precipitation commenced.

][/b]The precipitation started off as all snow in the Triad with surface temperatures in the mid to upper 30s with temperatures quickly falling into the 33-36 range within an hour or two of precipitation onset. Further east in the Triangle area, the precipitation fell as a mix of rain and snow for much of the afternoon and early evening with surface temperatures falling into the 35-39 range within an hour or two of precipitation onset. The precipitation did not change over to mostly or all snow in the Triangle area until mid to late evening.

Now let me get one thing straight, I'm not saying this is the same storm but as far as temps go they were very similiar. If the Euro is correct (which at this point it probably is not) I find it VERY hard to believe that you would not get SOME accumulating snow. I'm not saying this as a weenie as I'm pretty reserved to the fact MBY will not get anything.

[burgertime]

12z GFS mems @ 60 & 66

Looking at the sn-fall maps, major difference between the euro is taking a heavy band into central, euro dried out quickly north of a line from LYH-RIC, consensus from these members does not support that.

We'll know for certain if the Euro is out to lunch if the ENS comes back totally different.

[SN_Lover]

Here is the write up for that event:

http://www4.ncsu.edu...cases/20100302/

A few highlights:

[/b]

Now let me get one thing straight, I'm not saying this is the same storm but as far as temps go they were very similiar. If the Euro is correct (which at this point it probably is not) I find it VERY hard to believe that you would not get SOME accumulating snow. I'm not saying this as a weenie

Ohh THAT event. haha yea the only reason there was accumulating snow east in the Piedmont, was because it happened during the nighttime. I was driving through troutman that day looking at snowfall rates of 1in per hour, with only a dusting on the ground. The ground kept on melting the snow from beneath and the suns radiation didn't help out at all. That should have been a 6in+ storm, but ground, air, and sun angle kept that to a dusting for areas that it occurred during the daytime. I know Charlotte only saw a dusting for a short period of time, that's when the video was probably taken.

[WeatherNC]

We'll know for certain if the Euro is out to lunch if the ENS comes back totally different.

Yeah, I would very shocked if most of the members are not north of the op, likely falling more in line with the global. Anyone with access to the euro geopotential maps care to give a recap of the 850 track. Based on where the band sets up and h5 look, I would guess upstate of SC near GSP to somewhere offshore just south of Cape Lookout. Thanks in advance!

[Tullioz]

Here is the write up for that event:

http://www4.ncsu.edu...cases/20100302/

A few highlights:

[/b]

Now let me get one thing straight, I'm not saying this is the same storm but as far as temps go they were very similiar. If the Euro is correct (which at this point it probably is not) I find it VERY hard to believe that you would not get SOME accumulating snow. I'm not saying this as a weenie as I'm pretty reserved to the fact MBY will not get anything.

There are several differences. The temperatures leading up to that event were about 10 degrees cooler than they are today. Around 50 as opposed to 60. Also, that storm was deepening as it got to the coast and deepened quickly there after. This one is remaining a consistent pressure as it passed to the South and off the coast. Also it was already a few millibars stronger than this is forecast to be at any point. Of course there is also the fact that the accumulations mainly came after sunset. It would be interesting to know the exact soil temperatures. While they were warm ahead of that system I doubt they were in the upper 40's to low 50's as they are today.

[burgertime]

Ohh THAT event. haha yea the only reason there was accumulating snow east in the Piedmont, was because it happened during the nighttime. I was driving through troutman that day looking at snowfall rates of 1in per hour, with only a dusting on the ground. The ground kept on melting the snow from beneath and the suns radiation didn't help out at all. That should have been a 6in+ storm, but ground, air, and sun angle kept that to a dusting for areas that it occurred during the daytime. I know Charlotte only saw a dusting for a short period of time, that's when the video was probably taken.

For CLT it was during the afternoon..I know because I shot the video. That was my point we had high soil temps, late in the day with just moderate snow for short bursts and still saw a dusting on the grass. That's why I just don't get how you could assume with what the Euro shows VERBATIM you would somehow not get any accumulation.

[Carvers Gap]

SE KY looks to be a big winner in this looking @ model consensus. The Nam totally dumps on them. Interesting, the NAM has a typical 1-2 degree warm bias at this juncture but, the GFS is presenting the warmer outcome here. Could possibly be a timing thing as NAM is quicker than the GFS with system overall progression. Although, it does appear that since the tweak to correct the GFS cold bias,it now has somewhat of a warm bias in the short range. I think I would lean toward the NAM here, just looking @ the setup.

This may be one of those times where SE KY gets plastered while adjacent areas across the mountains in SWVA gets much less or much more in the way of a cold rain. IF NE windflow occurs throughout as depicted by much of the guidance, downsloping might be an issue off the High Knob landform in far SWVA as opposed to some upslope or neither over in SEKY. I've saw this many times. i.e.; Harlan and Middlesboro would get plastered while Jonesville to Gate city got very little in the way of snowfall.

So, in a nutshell, as far as the SE/KY , SW/VA , NE/TN area, right now it looks like the above mentioned scenario is likely, where an area north and west of a line along the VA/KY border across most of Wise CO, Va/Russel and northern Washington County, VA would get the heavy snowfall. i.m.o..

Hopefully, we get more of a northerly wind trajectory, or more cold advection than advertised and areas south and east of that line can get in on the heavy duty white stuff.

This is the third time I've asked this. I'm getting conflicting signals for KTRI. I don't have access to maps. Gawx mentioned ~6 inches, but I'm not seeing that on PSU's ewall and cannot tell due to time increments. I want to believe those amounts but 6 inches seems high w the warm nose...

[MillerA]

GSP afternoon discussion:

Short term /Saturday night through Monday/...

as of 220 PM Friday...used a GFS/European model (ecmwf) blend...which is also in line

with the UKMET...Canadian and global emsemble runs... while the NAM

remains an outlier. With this slightly slower timing in mind...

expect upper wave to push in from the west-southwest Sat night...across the

area sun and off the East Coast Sun night. An 850 mb low will drive east-northeast

across the lower MS valley Sat night and into the S Appalachians and

Carolinas sun. We will continue categorical probability of precipitation Sat night-Sun morning

with a gradual decrease in probability of precipitation Sun afternoon-evening as system tracks east and

drier air comes in behind the low. Thickness and temperature profiles still

indicate a mostly rain scenario through midday sun...then with colder

air and lower thickness values coming in behind the low expect rain to

mix with and turn to snow at higher elevs over the mountains by late

afternoon...then turning to snow across all the mountains and into the NC

foothills as precipitation tapers off and ends with a brief northwest flow

configuration after midnight sun.

Best quantitative precipitation forecast remains S of the County Warning Area with up to 1.5 inches storm total

precipitation expected across the far S tier and 3/4 to 1 inch across most

of the County Warning Area. Up to 2 in snow will be possible over some of the higher

peaks and ridges with this event but little accumulate is expected in

population areas. GFS BUFKIT soundings show that although there is a

warm nose aloft over the mountains late in the event...it is high enough

where precipitation should refreeze before reaching the ground and with

just a chance to slight chance pop by then...not expecting it to be a

problem at this time. Will need to keep an eye on this. Upper ridge and surface

high pressure build across the area Monday and after a cool start...temperatures

warm to about a Cat below average Monday afternoon.

[burgertime]

There are several differences. The temperatures leading up to that event were about 10 degrees cooler than they are today. Around 50 as opposed to 60. Also, that storm was deepening as it got to the coast and deepened quickly there after. This one is remaining a consistent pressure as it passed to the South and off the coast. Also it was already a few millibars stronger than this is forecast to be at any point. Of course there is also the fact that the accumulations mainly came after sunset. It would be interesting to know the exact soil temperatures. While they were warm ahead of that system I doubt they were in the upper 40's to low 50's as they are today.

The point was about soil temps and not being able to accumulate. The highs for 2 days before was 54 for both days. It might have been a different setup but it was still a dusting for snow falling in the afternoon in March with high soil temps.

[SN_Lover]

For CLT it was during the afternoon..I know because I shot the video. That was my point we had high soil temps, late in the day with just moderate snow for short bursts and still saw a dusting on the grass. That's why I just don't get how you could assume with what the Euro shows VERBATIM you would somehow not get any accumulation.

That was barely a dusting. Nobody here is saying warm ground temps will result in no snow. the snow ratios for that event was REALLY low. To get .005in out of a potential 6+ storm is not what I would even qualify as even a dusting. Like it or not downsloping will make a dry slot, that's into to met knowledge. that on top of the low pushing warm air loft ahead of the storm, paint's a grim scenario for KCLT at least.

I would not trust the a low resolution model to predict snow in a local location. The euro show's the dry slot, but in very poor resolution. Look to higher resolution models as we get closer.

[NCMET]

Good writeup sir...thank you

My snow forecast

http://www.examiner....-sunday-evening

[Tullioz]

The point was about soil temps and not being able to accumulate. The highs for 2 days before was 54 for both days. It might have been a different setup but it was still a dusting for snow falling in the afternoon in March with high soil temps.

It's late here so this will in all likelihood be my last post. I doubt that soil temperatures were as high as they are going into this event especially if temperatures rise into the low 60's again tomorrow and will likely be near 50 overnight Saturday. Temperatures don't really start falling until the storm is underway. Yes the soil temperatures will fall, but they will have a lot further to go. Taking the latest Euro at face value, a slushy accumulation is a possibility for most in NC, but that is more dependent on the rate that it falls more than soil temperatures. If snow is heavy enough you can get slush to build up regardless of ground temperatures. That being said, it is difficult to get any real accumulations and even if you do it will melt within a few hours anyway.

[tnweathernut]

This is the third time I've asked this. I'm getting conflicting signals for KTRI. I don't have access to maps. Gawx mentioned ~6 inches, but I'm not seeing that on PSU's ewall and cannot tell due to time increments. I want to believe those amounts but 6 inches seems high w the warm nose...

It looked like 2-3 to me, but I don't have access to any raw data. Maybe that is what Larry is basing the approximate 6 inches off of.

[Isopycnic]

DT's Foe-cast...

http://a3.sphotos.ak.fbcdn.net/hphotos-ak-ash4/396270_316497751730823_129478830432717_867617_1016053198_n.jpg

[burgertime]

That was barely a dusting. Nobody here is saying warm ground temps will result in no snow. the snow ratios for that event was REALLY low. To get .005in out of a potential 6+ storm is not what I would even qualify as even a dusting. Like it or not downsloping will make a dry slot, that's into to met knowledge. that on top of the low pushing warm air loft ahead of the storm, paint's a grim scenario for KCLT at least.

I would not trust the a low resolution model to predict snow in a local location. The euro show's the dry slot, but in very poor resolution. Look to higher resolution models as we get closer.

Follow me here, I'm arguing what was said that accumulation outside of the mountains would not happen. Even the Euro gives us very little IF it is to be believed. However further north at say GSO or Winston based on the Euro would get accumulating snowfall. I was using that event in Charlotte to show you can still get something in some of the worst conditions, such as warm soil, afternoon, sun angle etc...If you were able to get good enough rates during this storm it could easily accumulate.

[Mr Bob]

I hate to be in disagreement with some well known mets, but i do not see a significant snowfall in east or northeast TN. I agree that 1 inch at KTRI is possible, but not probable. There is a distinct warm nose that is depicted on the modeling and that warm nose absolutely loves to hang on. I don't see any reason to be against it. For TN my call is:

Nashville - inch or less

Knoxville - 1/2 inch or less

Cookeville and Crossville - 2-4 inches

Tricities - inch or less

Chattanooga - 0

East TN mountains - 1-2, another 1 possible in backlash/upslope

Big winners west of the apps - southeastern/eastern KY, southwest Virginia (4-6 inches, locally 8)

As for NC, I have no idea

I am with you! I don't like this one at all for eastern valley especially...

[SN_Lover]

Follow me here, I'm arguing what was said that accumulation outside of the mountains would not happen. Even the Euro gives us very little IF it is to be believed. However further north at say GSO or Winston based on the Euro would get accumulating snowfall. I was using that event in Charlotte to show you can still get something in some of the worst conditions, such as warm soil, afternoon, sun angle etc...If you were able to get good enough rates during this storm it could easily accumulate.

Ok. I understand that they Euro is painting snow up North. I am just saying that we don't yet know how severe the dry slot will be and how much precip makes it over the mtns. I really hope the Europ does come true though. I think it would accumulate too, but with really low snow to precip ratios. But we are in Feb so hopefully the incoming radiation wont be too bad and give us accumulation.