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Feb 12-13 Sleet/Snow/ZR Event


JoshM

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keep in mind it is hard to say with the mean as just averages out everything. But I would say most likely as the wedge erodes wednesday afternoon/evening Fayetteville would end as rain, but it still implies a hefty thump Tuesday night/Wednesday. The ECMWF ENS mean snow (again keep in mind this takes ice into account as well) still shows slightly over 7 inches a little more even than RDU. It looks like the best band of frontogenesis will set up from NE GA across the NC/SC border Tuesday night/Wednesday which will mean a corridor of moderate to heavy precip. So a lot of that could fall before any changeover.

Burger, Allan, many thanks! I wasn't too concerned about whether or not we'd be getting front end snow, given the soundings for the first wave. But all the ice talk down in the Palmetto State was (and is) worrisome. If the cutoff is over to cold rain, we'll take that and go home happy. Interesting day ahead.!

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Burger, delta, lookout or Larry... One thought I'm thinking this morning and would love your opinion on.

If the first punch drops we'll say 2" of snow north of I-20 up through the 85 corridor up through SC, the the high pressure slides in to place, in my mind this creates a virtual "slide" if you will, and could possibly enhance the CAD south and west?

Larry, having lived in East Gwinnett all my life, I cannot remember a cad event with snow on the ground initially or immediately in this case.

Thoughts?

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Keep this in mind to guys. THe GFS shows our primary s/w in the southern stream moves on shore into California tonight. So it is certainly possible we see more flips and flips today with a solid consensus starting in some regard with the 00z/06z guidance and definitely 12z tomorrow.

 

Yep. It aint over till it's over. With so much energy floating around as well changes are more than likely to come. 

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Burger, delta, lookout or Larry... One thought I'm thinking this morning and would love your opinion on.

If the first punch drops we'll say 2" of snow north of I-20 up through the 85 corridor up through SC, the the high pressure slides in to place, in my mind this creates a virtual "slide" if you will, and could possibly enhance the CAD south and west?

Larry, having lived in East Gwinnett all my life, I cannot remember a cad event with snow on the ground initially or immediately in this case.

Thoughts?

 

I really have no clue. I don't know though if it would really have enough time to enhance the CAD it certainly couldn't hurt. The problem is going to be getting 850's cold enough for you guys. I personally think there is going to be more sleet associated with this as you head south vs. ZR for many. 

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@78 on the GFS individual maps every panel has snow for WNC. The majority are 3+ inches. 

 

Yeah.. a few of them perform very well with the second wave... about as well as the NAM was doing for the first wave yesterday.

 

Almost all jackpot areas looking at the individual panels are the I-85 areas and/or Hwy 74 corridor.  THe "weakest" panel still puts down 5-6" for CLT.  All the others range from 7 to 10".

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Burger, delta, lookout or Larry... One thought I'm thinking this morning and would love your opinion on.

If the first punch drops we'll say 2" of snow north of I-20 up through the 85 corridor up through SC, the the high pressure slides in to place, in my mind this creates a virtual "slide" if you will, and could possibly enhance the CAD south and west?

Larry, having lived in East Gwinnett all my life, I cannot remember a cad event with snow on the ground initially or immediately in this case.

Thoughts?

 

Interesting point.  I would have to agree with you that having a fresh snow cover in the piedmont of nc/sc would have an impact on the developing CAD.

 

I personally think this is going to be bad for eastern GA/SC midlands in terms of freezing rain.  Classical CAD setups ALWAYS overperform in terms of surface temps.  I expect this storm will be no different. Short range models will start coming in colder and colder at the surface over the next day or two. IMO

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Keep this in mind to guys. THe GFS shows our primary s/w in the southern stream moves on shore into California tonight. So it is certainly possible we see more flips and flips today with a solid consensus starting in some regard with the 00z/06z guidance and definitely 12z tomorrow.

Yes, the models seem to be showing many different possibilities from run to run. Two hits to one hit back to two hits. More snow sometimes, more ice other times, and the locations change. Sounds like it would be very hard to forecast exactly what we will see with this.

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One thing that does worry me is that the models almost always under estimate the warm air aloft.  I am right on the line of staying snow for the whole event or getting almost all sleet.  I could see this thing playing out where an Athens to GSP to Charlotte line get’s nothing but sleet and freezing rain.  

 

IMO, the best place you could be right now would be SW NC around the GA/SC/NC border.  It seems like precip is maximized there and they have enough latitude to not be concerned with the warm nose.  

 

Hopefully that’s not the case!

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00z ECMWF ENS mean snow actually beefred up a little for RDU up to 7 inches now with a healthy 16 or so of the 50 members showing 9 or more.

 

The ecmwf ens mean low track is a good deal further east than the operational ECMWF. I think op Euro taking the low up the coastal plain is too far west. That forces RDU over the rain probably after a 0.5 of QPF which is some snow mostly ice.

Yeah, I think the 500mb energy phases/ amplifies a bit too much as this lifts northeast. It kind of explodes at hours 96-114 with the energy closing off, and because of that the SFC low gets drawn more westward.

post-390-0-94043400-1391952276_thumb.png

 

 

Like you mentioned, the mean is a bit further east, but the mean SFC temps overall line up very nicely with the operational. 

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This is one thing that has been shown over the past few days.

Yeah.. a few of them perform very well with the second wave... about as well as the NAM was doing for the first wave yesterday.

 

Almost all jackpot areas looking at the individual panels are the I-85 areas and/or Hwy 74 corridor.  THe "weakest" panel still puts down 5-6" for CLT.  All the others range from 7 to 10".

 

No matter what any model states, this is always a worry round these parts. The SPC meso page will be getting worked over come Tomorrow night thru Thursday. :)

One thing that does worry me is that the models almost always under estimate the warm air aloft.  I am right on the line of staying snow for the whole event or getting almost all sleet.  I could see this thing playing out where an Athens to GSP to Charlotte line get’s nothing but sleet and freezing rain.  

 

IMO, the best place you could be right now would be SW NC around the GA/SC/NC border.  It seems like precip is maximized there and they have enough latitude to not be concerned with the warm nose.  

 

Hopefully that’s not the case!

 

 

Let the WV watch start..

sat_wv_west_loop-12.gif

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Please; anyone in SC (especially the midlands) PLEASE pay attention to the modeling..  Lookout pretty much crushed my dreams of it missing us.. and we are absolutely screwed in the midlands if the current modeling is correct.

 

ANYONE around the midlands of SC.. if this ice storm happens as modeled as of 00z tonight..(maybe even a bit south of here) please once again keep up to date on these forums etc.  This is a really delicate situation.  I'm scared... and if close to 1.5-2 inches of ZR is coming here; I'm leaving the state.

I am very interested in Stormsfury opinion of this situation.  He is very good with analyzing CAD situations.  In the last big icestorm (can't remember the yr), he nailed it perfectly.

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I have always said this since living in GA and knowing anything about the weather.  There is ALWAYS 1 thing I can count on when it comes to the potential for wintry weather (when that threat is there, not all wedges) is that models will ALWAYS be too warm at 2m and will always trend colder as we get closer.  I know its been said a bunch of times on the board the last few days, and burrell just said it again, but wedge tend to always OVER PERFORM around here, and while this one is not the strongest (MB) its over a VERY cold airmass with snow cover and sticks in there pretty damn well.  I might be super going out on a limb here, but I think ATL-AHN and AGS-CAE  (and maybe back to MNC-CSG) gets HAMMERED with a ZR fest with that 2nd wave...

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Burger, delta, lookout or Larry... One thought I'm thinking this morning and would love your opinion on.

If the first punch drops we'll say 2" of snow north of I-20 up through the 85 corridor up through SC, the the high pressure slides in to place, in my mind this creates a virtual "slide" if you will, and could possibly enhance the CAD south and west?

Larry, having lived in East Gwinnett all my life, I cannot remember a cad event with snow on the ground initially or immediately in this case.

Thoughts?

 

It's something I've pondered recently but I honestly don't know. I've never seen a cad situation where there is already snow and ice on the ground here or just upstream. One would think it would tend to work toward having things stay cold, especially during the daytime.

 

It's interesting to note though that the first wave has been trending ever so slightly colder aloft the last 36 to 48 hours on most of the modeling. It's important because soundings indicate it's clearly only a rain vs snow situation. I wouldn't expect much sleet or freezing rain with it.

One thing that does worry me is that the models almost always under estimate the warm air aloft.  I am right on the line of staying snow for the whole event or getting almost all sleet.  I could see this thing playing out where an Athens to GSP to Charlotte line get’s nothing but sleet and freezing rain.  

 

IMO, the best place you could be right now would be SW NC around the GA/SC/NC border.  It seems like precip is maximized there and they have enough latitude to not be concerned with the warm nose.  

 

Hopefully that’s not the case!

If I was in north carolina where you still could be snow,  I would be worried about that for the second wave. With the first wave, there isn't a waa regime but during the second wave there is strong waa aloft. So if the warm air is underestimated I would tend to think it would be with the second wave.

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I have always said this since living in GA and knowing anything about the weather.  There is ALWAYS 1 thing I can count on when it comes to the potential for wintry weather (when that threat is there, not all wedges) is that models will ALWAYS be too warm at 2m and will always trend colder as we get closer.  I know its been said a bunch of times on the board the last few days, and burrell just said it again, but wedge tend to always OVER PERFORM around here, and while this one is not the strongest (MB) its over a VERY cold airmass with snow cover and sticks in there pretty damn well.  I might be super going out on a limb here, but I think ATL-AHN and MCN-AGS-CAE  (and maybe back to CSG) gets HAMMERED with a ZR fest with that 2nd wave...

I agree with you  :(   I learned that lesson back when SF,Queen,etc took LC to the woodshed...lol.  It's gonna be nasty for those from mcn to cae with temps at the freezing mark. 

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I have always said this since living in GA and knowing anything about the weather.  There is ALWAYS 1 thing I can count on when it comes to the potential for wintry weather (when that threat is there, not all wedges) is that models will ALWAYS be too warm at 2m and will always trend colder as we get closer.  I know its been said a bunch of times on the board the last few days, and burrell just said it again, but wedge tend to always OVER PERFORM around here, and while this one is not the strongest (MB) its over a VERY cold airmass with snow cover and sticks in there pretty damn well.  I might be super going out on a limb here, but I think ATL-AHN and MCN-AGS-CAE  (and maybe back to CSG) gets HAMMERED with a ZR fest with that 2nd wave...

I would urge a little caution here though because this actually does not evolve like our typical cad storms. Most times the cold and dry air is already in place and the models will miss the evaporational cooling aspect of it..and thus end up being too warm. But with this it's already saturated and we have to lean only on cold air advection. I think this partly explains why there isn't much difference between the euro and gfs as far as surface temps go. (normally the gfs is a little colder than the euro) So it will be interesting to see how this plays out, especially if there is a good bit of snow on the ground in some areas.

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It's something I've pondered recently but I honestly don't know. I've never seen a cad situation where there is already snow and ice on the ground here or just upstream. One would think it would tend to work toward having things stay cold, especially during the daytime.

 

It's interesting to note though that the first wave has been trending ever so slightly colder aloft the last 36 to 48 hours on most of the modeling. It's important because soundings indicate it's clearly only a rain vs snow situation. I wouldn't expect much sleet or freezing rain with it.

If I was in north carolina where you still could be snow,  I would be worried about that for the second wave. With the first wave, there isn't a waa regime but during the second wave there is strong waa aloft. So if the warm air is underestimated I would tend to think it would be with the second wave.

 

Lookout, 

 

What kind of a feel are you getting for your backyard?  I’m sure you’ve spent some time looking at soundings. Do you think you can get in on some snow accumulations with the first wave? Based on the soundings I have seen, it appears the cutoff for snow with the first wave is roughly I-85.  South of there it looks like a slight warm nose around 850mb is trying to teeter totter above freezing.  Of course, I’m basing this mainly off the NAM soundings, which seems to be on the warm side of guidance right now.

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