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January 6th-7th Potential Storm

SimeonNC said:
Yeah I've noticed that the models are really quick to erode the CAD, even the RGEM.

Also, you know more than me but I feel like the HP in Canada makes this more of a hybrid thab in-situ
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This is from GSP
Meanwhile, the remnant high
pressure to the east sets up an in-situ wedge of colder air ahead of
the precip. How much cold air remains in place at the onset of
precip is not entirely certain, but should be enough to allow for
near freezing temps well before daybreak.

Im not a good teacher but here's a rundown. In-Situ CAD setup is one in which little or no cold air advection is occurring because the high pressure center which we relied on in the classic setup is too far to the south. Cold air is established through evaporational cooling caused by a pool of dry air east of the Appalachians.
 
SNOWMANN said:
This is from GSP
Meanwhile, the remnant high
pressure to the east sets up an in-situ wedge of colder air ahead of
the precip. How much cold air remains in place at the onset of
precip is not entirely certain, but should be enough to allow for
near freezing temps well before daybreak.

Im not a good teacher but here's a rundown. In-Situ CAD setup is one in which little or no cold air advection is occurring because the high pressure center which we relied on in the classic setup is too far to the south. Cold air is established through evaporational cooling caused by a pool of dry air east of the Appalachians.
Click to expand...
Thanks
 
GSP gets that typically models tend to underestimate the CAD and relying on the cold biased ones. Can’t say I’m surprised tbh. East Flat Rock, Chimney Rock, and especially Saluda, Tryon, and Landrum do exceptionally well in these setups. I’ve seen plenty of times these last 3 years where I get a Trace to a tenth of inch and 10 minutes up the road in Tryon they’re sitting at a qtr to a third of inch. And Saluda will be sitting at half an inch plus.
 
zr_acc-imp.us_ma.png
 
Cad Wedge NC said:
Dews will only tell part of the story, You have to look at wet-bulbs if you want a true comparison.
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I'm going to pay very close attention to not only where DPs bottom out during the evening but also do they rise as fast as the NAM is showing as precip approaches. If in reality we are sitting in the mid to upper teens for dews that evening vs the low 20's and generally hold to the low 20's as precip arrives, I think there's a solid chance at some icing. Also paying attention to where the temps are sitting around 10pm. Are we sitting around 33-35 with Dews in the low 20's or are we sitting in th mid to upper 30's range? Noway to know until tomorrow night.
 
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First call Map. I went with something closer to GSP's thinking. Feel confident that Brevard, Hendersonville, Saluda, Tryon/Landrum, Chimney Rock get a pretty significant icing event. Saluda takes the cake for holding onto low level cold air. I think the high country gets close to 0.25" and the French Broad River Valley ends up with a solid 0.1"+. The escarpment probably gets a legit ice event out of this. Areas to the west and south are the question marks. The foothills I think have a good shot for as much as 0.25" but at least 0.1". The northern upstate (especially along and north of 85 and east of highway 25) get some icing, but how much is really up in the air. Could be a trace, could be enough to cover the tops of tree, could be more. Just south of 85 through the piedmont probably end up with a trace with areas further north getting up to a tenth of an inch.

Like I said above areas along the border and the piedmont it's really a nowcasting type of thing. If the CAD is being underdone and you get a footprint and higher icing like the CMC/RGEM/CAMS. If we're sitting around 10pm with DP in the upper 20's and temps in the mid 30's similar to the NAM/3K/HRRR, then yeah don't expect much if any ZR. Really is a waiting game around this way.
 
Ice forecast. This looks mainly like a foothill/escarpment deal. Cities in the Piedmont/upstate could get a quick glaze for a hour or so then a quick flip to cold rain, areas like hickory will probably stay ZR for a bit longer as usual, and the escarpment might struggle to get above freezing until late morning/lunchtime B5766308-5F6B-43F0-95C5-DA134E302418.jpeg
 
19.8/17 here this morning..... wasn't expecting it to get that low last night. That will certainly drop those soil temps. It may also play a part in how long we keep the sub-freezing temps tomorrow.
 
This is forecasted to be a nada burger in mby. But Ill track for the fun of it, under a winter wx adv. Forecasted to cloud up around 6z tonight. Clear skies as the sun goes down. So will fall of todays forecasted high of 44 down to freezing by 8pm easily. Cloud deck should be rolling in by midnight. That will trigger a 2-3 degrees bounce back up before precip begins, then we wetbulb back down. Always fun to see unfold as models usually are off a degree or 2. sometimes forecast to warm, sometimes to cold.
Regardless / COLD RAIN on tap for Saturday which beats 90 degrees with a dewpoint of 70 any day of the week!
 
Well got down to 24 here this morning, below the forecast. Could impact degree of heating today so something to monitor today/this evening for any potential ZR overnight.
 
Cad Wedge NC said:
19.8/17 here this morning..... wasn't expecting it to get that low last night. That will certainly drop those soil temps. It may also play a part in how long we keep the sub-freezing temps tomorrow.
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22.1 here this morning with mega frost, even some frosty tree tops around creeks and swampy areas. I don't have a dog in this potential storm fight, but, I'll be shocked if temps aren't a touch cooler tonight than model forecast and precip doesn't arrive a tick sooner (almost always does) giving a glancing blow to at least western triangle counties.
 
metwannabe said:
22.1 here this morning with mega frost, even some frosty tree tops around creeks and swampy areas. I don't have a dog in this potential storm fight, but, I'll be shocked if temps aren't a touch cooler tonight than model forecast and precip doesn't arrive a tick sooner (almost always does) giving a glancing blow to at least western triangle counties.
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Yeah, I think eventually they may have to add Orange and Durham(mostly for NW Durham) to the advisory.
 
Hrrr has a pretty solid event for areas along the escarpment, if there’s a surprise for higher then forecasted ice, it would be those areas B11D7685-D6F6-41E7-B5F2-F9DE9D1B9586.png
 
metwannabe said:
Canadians are adjusting to reality I see. Still think NW Durham and NW Granville (just to name a couple of spots locally) still start as a very brief zr before flipping fast but this is escarpment's baby.
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I'd agree with that, especially between 85 and 158. North of 158 may hang on for a bit longer.
 
metwannabe said:
Canadians are adjusting to reality I see. Still think NW Durham and NW Granville (just to name a couple of spots locally) still start as a very brief zr before flipping fast but this is escarpment's baby.

View attachment 140035
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These models suck for these marginal events. Often way to cold time and time again. Decent during deep cold CAD events though. But kinda figured there were out to lunch, hence why I didn’t share the RGEM
 
Interesting from FFC. Pretty bullish for Dahlonega/ Cleveland area:

URGENT - WINTER WEATHER MESSAGE
National Weather Service Peachtree City GA
1224 PM EST Fri Jan 5 2024

GAZ006>009-014>016-060200-
/O.CON.KFFC.WW.Y.0001.240106T0400Z-240106T1300Z/
Fannin-Gilmer-Union-Towns-Dawson-Lumpkin-White-
Including the cities of Dahlonega and Cleveland
1224 PM EST Fri Jan 5 2024

...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 11 PM THIS
EVENING TO 8 AM EST SATURDAY...

* WHAT...Freezing rain expected. Total ice accumulations of
around one-tenth of an inch, with ice accumulations of up to
two- tenths of an inch possible in the highest elevations of
far northeast Georgia. Winds gusting as high as 30 mph.

* WHERE...Portions of north central and northeast Georgia.

* WHEN...From 11 PM this evening to 8 AM EST Saturday.

* IMPACTS...Difficult travel conditions are possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. Prepare for possible
power outages.
 
41 in Asheville. up from 22 this morning with the sun out. Cloud cover tonight should limit temps from going down fast. Thinking I'm out of the game for anything wintry. Hopefully everyone in the CAD areas gets a nice storm and doesn't loose power.
 
1704480170761.png
Updated map. I'm expecting around a tenth of inch or less in mby. The sweet spot is still going to be from Brevard to Hendersonville, Saluda, and Chimney Rock. The far western foothills and closest to the escarpment get 0.25"+. Further east drops off considerably. 85 corridor probably gets a trace to maybe 5 hundredths of an inch at most.
 
iGRXY said:
View attachment 140068
Updated map. I'm expecting around a tenth of inch or less in mby. The sweet spot is still going to be from Brevard to Hendersonville, Saluda, and Chimney Rock. The far western foothills and closest to the escarpment get 0.25"+. Further east drops off considerably. 85 corridor probably gets a trace to maybe 5 hundredths of an inch at most.
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highly doubt any ZR makes it into Spartanburg county other then the extreme far northern fringes, even the colder models like the nam don’t show ZR down there anymore
 
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