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January 6th-7th Potential Storm

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CMC expanding the footprint more this run down in the upstate.
 
LickWx said:
The real question is…. will the 5000 foot peaks in upstate sc combined with the ICON running too warm combined with the dew points verifying lower and the NAM eroding CAD too fast lead to an epic ice storm that the NWS and models just aren’t grasping?
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I don't recall any 5,000 ft peaks in upstate South Carolina.
 
Cad Wedge NC said:
I don't recall any 5,000 ft peaks in upstate South Carolina.
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You can always count on him coming onto a weather thread to make corny posts that a 12 year old could come up with and not actually discuss the weather on a … wait for it … weather forum. Very on par and typical for him.
 
Official morning briefing

Winter Storm Watch Issued….


WINTER STORM WATCH IN EFFECT FROM LATE FRIDAY NIGHT THROUGH
SATURDAY AFTERNOON...

* WHAT...Heavy mixed precipitation possible. Total snow and sleet
accumulations of up to a half inch and ice accumulations of two
tenths to one quarter of an inch possible. Isolated areas could
see ice accumulations up to three tenths of an inch.

* WHERE...Portions of piedmont and western North Carolina.

* WHEN...From late Friday night through Saturday afternoon.

* IMPACTS...Plan on slippery road conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is a potential for significant
snow, sleet, or ice accumulations that may impact travel.
Continue to monitor the latest forecasts.
 

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For those worried about a debilitating ice storm in GSP or CLT:
As of 07 UTC, the NBM has very low chances of ZR for GSP or CLT. In fact for GSP, the trace of snow chances are higher.
 
GSP Morning AFD Discussion 01/04 3:00am

The aforementioned low-level jet will establish a pronounced warm nose across the area before the column fully saturates with the warm nose strongest across eastern portions of the area. Wetbulbing via saturation of the dry airmass will help establish an in-situ wedge of cold air east of the mountains. Sub-freezing wetbulb temperatures will be common at precipitation onset from the mountains through the North Carolina foothills and Piedmont, especially deeper into the wedge along and north of I-40. Thus, a mixed bag of precipitation types is expected Friday night into Saturday morning. A brief period of snow is expected across the mountains before the strengthening warm nose switches things over to sleet and then freezing rain.

Farther east, in the in-situ wedge, freezing rain will be the predominate precipitation type with a brief period of sleet possible across the northern foothills. Without a sustained source of cold dry air, and given the self limiting process of freezing rain due to latent heat release, all locations will eventually see surface temperatures warm above freezing. This will occur quickest on the edges of the in-situ wedge with the northern foothills and mountains the last to see temperatures rise above freezing late Saturday morning. Pretty much everyone should be seeing a cold rain by noon, if not earlier.

The question now turns to how much snow/sleet/ice accumulation can be expected. The quick transition to ice across the mountains will limit snow/sleet totals to 1-2" followed by 0.05-0.2" of ice. In the in-situ wedge, marginal wetbulb temperatures and light winds will lead to modest ice accretion at best with most places on the edge of the wedge seeing a lot of runoff and less freezing of the rain. A few hundreths of an inch of accretion will be possible along I-85 before quickly warming above freezing with roughly 0.1-0.2" along a line from Statesville to Hickory to Rutherfordton and Columbus.

Historically, even during in-situ wedge regimes, the foothills immediately against the Blue Ridge escarpment, especially along and north of I-40 tend to hold on to sub-freezing air the longest and have proven to be stubborn to warm. Guidance often struggles to resolve this with the NAM often having the best handle on low-level thermal profiles in wedge airmasses. Thus, more weight was given towards the NAM thermal profiles, which supports a longer duration of freezing rain against the escarpment. In addition to climatological support, probabilistic guidance also paints this area as the location most likely to have the potential to receive warning criteria ice accretion. As such, a winter storm watch has been hoisted from Alexander/Caldwell counties southwest along the escarpment through Henderson and the mountains of Polk county. The highest ice totals are expected to occur in this corridor from Lenoir to Marion to Lake Lure and Hendersonville. Eventually, winter weather advisories will be needed across the surrounding counties where ice accretion is expected. Two limiting factors that could result in less ice would be temperatures warming quicker than currently forecast and the potential for deep convection along the Gulf Coast to inhibit greater inland moisture transport and reduce available QPF. A period of northwest flow snow showers will also be possible along the Tennessee border Saturday night
 
Right now I think T- 0.1” from Highway 74 down to 85 corridor in the upstate. 0.1”-0.25” across the eastern escarpment and the foothills. Places like Saluda, Hendersonville, chimney rock tend to really over-perform and wouldn’t surprise me to see them get isolated 0.25”-0.33” amounts. I’m thinking a tree and porch topper here. Maybe a light glaze on the bushes. Probably will make a map this evening if things hold.
 
There's roughly a 3 degree difference between the NAM and RGEM. It's a real throw of the dice whether its the RGEMs cold bias or the RGEM being good at CAD. If the RGEM is right this is a warning criteria event for the foothills and at least advisory for the piedmont and upstate. For what it is worth, the super duper long range HRRR seems to agree with the RGEM.
 
It doesn't appear this system will produce any meaningful snowfall on its northern fringe. Where there is deep moisture, the boundary layer is too warm for accumulations other than quick, rate driven ones. I was hoping to find a good 3-5" swath to take the kids to. Am I missing something or is this the reality?
 
SNOWMANN said:
There leaning towards the insitu Cad hanging on longer than modeled especially the typical areas 1-40N to right along the escarpment.
Never fails.
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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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