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Wintry The Webber/1300m/Kylo/Jon/Whatalife Storm January 12th-14th

BHS1975 said:
Need to be in the uppers 20s or less for decent accrual with is very rare in wake.
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Based on my experiences with icestorms as well as reading old newspapers for storms not experienced, large accrurals can occur even at 31 (and on occasion even almost to 32), especially if the precip rate is not heavy. Interestingly, my research showed me that one of the worst icestorms on record at ATL, Jan of 1973, actually had the bulk of the ZR with temps 30-31. And much of the precip was actually falling heavily. The low was 30.
 
SnowNiner said:
Look how light the precip is on the NAM 3k. Where is all its ice coming from? I'm not sure where all the precip is coming from from this storm, it seems like how north it is and how it moves, it being a Miller B (you can see the dry slot), the qpf would be light. I tend to lean that the precip will be light.

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We shall see if the qpf is correct on the RGEM or the 3k NAM, the RGEM is showing qpf of 1-1.4 so that's where all that ice is coming from in the map I posted..... but I agree it may be overdone.
 
Kylo said:
The EPS is usually pretty good with precip forecast. Dampens out any spurious op or meso runs.

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Yeah I think a good rule is to use EPS for precip amounts and your short range hi res models for thermal profiles.... Difficult part for forecasters imo is those short range hi res models are very similar but differ by a degree or two which makes all the difference in the world of a non-event to nuisance event to major winter storm
 
GaWx said:
Based on my experiences with icestorms as well as reading old newspapers for storms not experienced, large accrurals can occur even at 31 (and on occasion even almost to 32), especially if the precip rate is not heavy. Interestingly, my research showed me that one of the worst icestorms on record at ATL, Jan of 1973, actually had the bulk of the ZR with temps 30-31. And much of the precip was actually falling heavily. The low was 30.
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We got 13 inches of snow in Dublin , Ga out of that and it snowed in Cuba. A friend's parent took them to Atlanta to see the snow. They got stuck in a 30 mile line of traffic that could not move trying to come back.
 
boobear said:
We got 13 inches of snow in Dublin , Ga out of that and it snowed in Cuba. A friend's parent took them to Atlanta to see the snow. They got stuck in a 30 mile line of traffic that could not move trying to come back.
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That 13” Dublin snow was from a storm a month later than the big ATL icestorm. Two different storms.

It snowed in Cuba?
 
metwannabe said:
Yeah I think a good rule is to use EPS for precip amounts and your short range hi res models for thermal profiles.... Difficult part for forecasters imo is those short range hi res models are very similar but differ by a degree or two which makes all the difference in the world of a non-event to nuisance event to major winter storm
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Also a big part of the temp profile is how quickly places cool down due to evap cooling and the timing of that. Something like the RGEM would like in the CAD because of all the qpf whereas the 3km NAM would be lighter and the temps wouldn't cool as effectively due to the spotty nature of the precip. This is a tough call for sure, I do think the 3km NAM is still too dry and will adjust upwards. The RGEM temp profile with about half the qpf might be a good bet at this time until we have further trends to observe.
 
snowlover91 said:
Also a big part of the temp profile is how quickly places cool down due to evap cooling and the timing of that. Something like the RGEM would like in the CAD because of all the qpf whereas the 3km NAM would be lighter and the temps wouldn't cool as effectively due to the spotty nature of the precip. This is a tough call for sure, I do think the 3km NAM is still too dry and will adjust upwards. The RGEM temp profile with about half the qpf might be a good bet at this time until we have further trends to observe.
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The RGEM looks to be amped though.
 
SnowNiner said:
Look how light the precip is on the NAM 3k. Where is all its ice coming from? I'm not sure where all the precip is coming from from this storm, it seems like how north it is and how it moves, it being a Miller B (you can see the dry slot), the qpf would be light. I tend to lean that the precip will be light.

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Charlotte is in a far more precarious position with this event than RDU.
 
Upstate SC anywhere north of 85 is not looking good. The short range models are picking up on the CAD better and more QPF as the almost always do better in CAD setups. We seen this with the DEC storm. Alot of areas are looking at an Ice storm I'm afraid.

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WxWatch said:
The RGEM looks to be amped though.
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It is a bit amped looking but could be correct also. A blend of it and the 3km NAM is probably the best idea right now until things clear up. Fwiw the GFS is showing over an inch of qpf in parts of NC too.
 
Bsud said:
Upstate SC anywhere north of 85 is not looking good. The short range models are picking up on the CAD better and more QPF as the almost always do better in CAD setups. We seen this with the DEC storm. Alot of areas are looking at an Ice storm I'm afraid.

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Someone needs to let Chris justice know this information. Because those folks over at channel 4 is insisting a cold rain. What’s scary is if this indeed happens know one will be prepared because local meteorologists has not called for a ice storm


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Jessy89 said:
Someone needs to let Chris justice know this information. Because those folks over at channel 4 is insisting a cold rain. What’s scary is if this indeed happens know one will be prepared because local meteorologists has not called for a ice storm


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But NWS GSP has had a mix in the forecast for 3 days.

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The GFS is a bit more modest...but what you may miss with this graphic is the .55 over Forsyth COunty.

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If it does indeed get icy in NC, would it be more of an issue with ice on trees and powerlines ? I'm guessing most of the major roads would be fine wouldn't they ?
 
snowlover91 said:
It is a bit amped looking but could be correct also. A blend of it and the 3km NAM is probably the best idea right now until things clear up. Fwiw the GFS is showing over an inch of qpf in parts of NC too.
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GFS also still looks little warmer, not handling the CAD well or due to more amped system? I think it's a fine line, imagine that, amped system means more qpf also means warmer and less wintry, sheared out weaker system, less qpf and colder but unable to maximize the CAD potential....
 
Jessy89 said:
Someone needs to let Chris justice know this information. Because those folks over at channel 4 is insisting a cold rain. What’s scary is if this indeed happens know one will be prepared because local meteorologists has not called for a ice storm


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We all know how some TV mets are. Sometimes they don't get on board until it's at the nowcasting stages or several hrs out.
 
SoutheastRidge said:
If it does indeed get icy in NC, would it be more of an issue with ice on trees and powerlines ? I'm guessing most of the major roads would be fine wouldn't they ?
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Actually with this current cold airmass in place and much of this occurring at night, roads could very well become treacherous Sunday morning..
 
Using the NCEP site for the FV 3, it looks like it has that front-end snow again for tomorrow, followed by a solid round of freezing rain overnight for the western Piedmont of NC.
 
metwannabe said:
GFS also still looks little warmer, not handling the CAD well or due to more amped system? I think it's a fine line, imagine that, amped system means more qpf also means warmer and less wintry, sheared out weaker system, less qpf and colder but unable to maximize the CAD potential....
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The OP GFS is HORRIBLE with CAD, by far the worst model I've seen at handling it. I remember last year there was a system that it didn't show snow for a lot of areas until about 12 hours out. I would not trust it's thermal profiles at all. The 3km NAM and RGEM are the best there is inside 48 hours and the way to go with thermals, usually a blend of the two works out very well.
 
Poimen said:
Using the NCEP site for the FV 3, it looks like it has that front-end snow again for tomorrow, followed by a solid round of freezing rain overnight for the western Piedmont of NC.
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I will be so glad when it is out of it's testing phase so we can finally put the GFS to rest and the FV3 data comes in timely....
 
Well, I think the biggest change and why the short range models are showing a colder solution is the low pressure center has taken a huge shift south. NAM is similar. Seems like the low pressure is strung out and the minimum pressure may be further south now thus creating less WAA. I don't know, but that change has peaked my interest back just a bit.


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Folks in the ATL metro area needs to be monitoring the potential for icy conditions as well. Right now, it looks like ATL metro will just be above freezing. 12km NAM is showing 1°c (33°f) at surface. It could trend colder, it wouldn't take much.
 
Brad still says maybe only a light glaze in clt, if models hold up at 06z tommorow, he needs to sound the alarm
 
snowlover91 said:
The OP GFS is HORRIBLE with CAD, by far the worst model I've seen at handling it. I remember last year there was a system that it didn't show snow for a lot of areas until about 12 hours out. I would not trust it's thermal profiles at all. The 3km NAM and RGEM are the best there is inside 48 hours and the way to go with thermals, usually a blend of the two works out very well.
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metwannabe said:
I will be so glad when it is out of it's testing phase so we can finally put the GFS to rest and the FV3 data comes in timely....
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I would definitely go with the FV3 and NAM combo over the GFS now, especially based on how well that combo did with the December storm and handling the CAD then.
 
From looking at all the models it simply boils down to several key factors.
1. How quickly does the precip arrive and is it spotty or steady? Spotty precip won't cool the atmosphere as effectively and delayed precip allows more time for airmass modification and less evap cooling.
2. Does the initial overrunning precip cross the mountains and drop a few inches of snow in parts of NC?
3. When the low transfers does it cause a precip minimum across a portion of the area thus lowering the qpf and cooling potential?

These three factors are incredibly difficult to predict. Global models do poorly with these types of situations and even the high res models struggle. A blend of the 3km and RGEM is what I would go with at this time and that is an icy mess with .5-.8 of qpf falling as sleet, freezing rain and maybe some light snow in the favored CAD regions of NC down into a small area in SC and GA.
 
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