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mackerel_sky

The January 7-8th possible CAD storm

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I would go out on a limb and say models are eroding the dry air out too quickly, and this may bring more sleet for Georgia and NC mountains and foothills than freezing rain where the moisture does overcome. Also some snow flakes are possible in the northern mountains before mixing. If this system can over perform in moisture the impacts would be huge I think because of recent cold wave. However, no indicators point to that, just going to have to watch upstream obs around west Georgia and Tennessee.

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WWA issued for west GA.  Other areas of north Georgia are being monitored for possible upgrade to WWA. 

 

Not sure which rule number it is but calling a storm dead because it misses your backyard is a big one you shouldn’t break.  GA may get nothing but this storm is far from a goner.   

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I do wish it were snow rather than ice that's being forecast, however...I can attest that the ground is frozen, and anything that falls out of the sky is going to freeze on contact. DOT has been proactive in my area, treating the roads with brine.

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Person-Forsyth-Guilford-Alamance-Davidson-Randolph-
1213 PM EST Sun Jan 7 2018

This Hazardous Weather Outlook is for central North Carolina.

.DAY ONE...This Afternoon and Tonight.

Hazardous weather is not expected at this time.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Light freezing rain and freezing drizzle will be possible Monday 
afternoon and early Monday night. A light glaze may result. 

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Way too dry which supports snow to sleet to ZR ultimately; may cut down on ZR totals west of i77. In the east, timing may allow dry air to eacape supporting less of a chance of sleet there but still possible briefly at the onset I think. Snow/sleet probs is highest northern mountains into Virginia. 

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1 hour ago, LithiaWx said:

WWA issued for west GA.  Other areas of north Georgia are being monitored for possible upgrade to WWA. 

 

Not sure which rule number it is but calling a storm dead because it misses your backyard is a big one you shouldn’t break.  GA may get nothing but this storm is far from a goner.   

I believe that some of the people calling the storm dead are in NC where it basically is. Us further SW stand a better chance since we get the precip sooner and will not warm as much with daytime heating.

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24 minutes ago, mackerel_sky said:

Unmmmm? Don't think this is a NC poster cancelling a thread?

That quote was in jest based off a post a little earlier in the thread.  

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This just posted here in Gwinnett County:

... WINTER WEATHER ADVISORY IN EFFECT FROM 6 AM TO 1 PM EST MONDAY... * WHAT... LIGHT FREEZING RAIN IS EXPECTED TO DEVELOP VERY LATE TONIGHT INTO MONDAY MORNING. TOTAL ICE ACCUMULATIONS OF A LIGHT GLAZE TO LESS THAN A TENTH OF AN INCH ARE EXPECTED. * WHERE... PORTIONS OF NORTH CENTRAL AND NORTHEAST GEORGIA. * WHEN... FROM 6 AM TO 1 PM EST MONDAY. * ADDITIONAL DETAILS... THE FREEZING RAIN WILL RESULT IN DIFFICULT TRAVEL CONDITIONS, INCLUDING DURING THE MORNING COMMUTE ON MONDAY. ELEVATED SURFACES SUCH AS BRIDGES AND OVERPASSES WILL BE MOST SUSCEPTIBLE TO ICING. PRECAUTIONARY/PREPAREDNESS ACTIONS... A WINTER WEATHER ADVISORY MEANS THAT PERIODS OF FREEZING RAIN WILL CAUSE TRAVEL DIFFICULTIES. BE PREPARED FOR SLIPPERY ROADS. SLOW DOWN AND USE CAUTION WHILE DRIVING.

 

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The models have been quite anemic with regards to precipitation tomrorow for WNC, but NWS GSP just hoisted WWAs for a good chunk of the area.  This may be one of those cases similar to last weekend in the mountains, where just a fraction of water will cause horrific travel conditions.  Kudos to GSP for going ahead and warning people of this issue.

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1 hour ago, Tanith said:

I do wish it were snow rather than ice that's being forecast, however...I can attest that the ground is frozen, and anything that falls out of the sky is going to freeze on contact. DOT has been proactive in my area, treating the roads with brine.

yep...although  it won't be a big total precip maker, it sure isn't going to take much to make the roads a mess.  Even prolonged freezing drizzle could cause some serious issues with temps way down in the 20s and a frozen ground. 

fwiw, the euro is quite a bit wetter than other runs and models...shows as much as 0.6 to .8 for atlanta. Probably overdone i'm sure since there is no support for it...although the gfs has been showing a narrow band of heavier totals too...except it has it over central ga. something to watch maybe. 

18z nam is coming in quite a bit wetter...closing in on 0.25 of an inch.  enough to make for some sure enough bad travel conditions in the morning. 

will be interesting to see what the temps do tomorrow regardless. the 18z nam is actually a little warmer...retreating subfreezing temps into northeast ga by afternoon...but with steady precip, it's doubtful. regardless, enough falls in the morning that it's close to warning criteria for western parts. 

 

 

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1 minute ago, calculus1 said:

The models have been quite anemic with regards to precipitation tomrorow for WNC, but NWS GSP just hoisted WWAs for a good chunk of the area.  This may be one of those cases similar to last weekend in the mountains, where just a fraction of water will cause horrific travel conditions.  Kudos to GSP for going ahead and warning people of this issue.

Yep was thinking the same until I just saw the 18Z nam. Pretty dang juicy. 

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1 minute ago, Red1976Red said:

I believe several GSP counties support snow/sleet, primarily mountains&foothills where dry air will be tough to scour out during the onset. But certainly favors freezing rain/drizzle as time wears on pretty much everywhere. 

Dry air or not mid levels are a furnace. This will be freezing rain.

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1 minute ago, CummingGaSnow said:

Everything hinges on precip here. If we get precip early enough to lock the CAD in, then I bet we get more than what we're thinking right now, especially in the prime CAD areas of NC/NE GA.

WWA now in effect for the entire 85 corridor in North Georgia.

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4 minutes ago, franklin NCwx said:

Dry air or not mid levels are a furnace. This will be freezing rain.

Any area that sees delayed or no precip will favor freezing rain for the event. Blacksburg has a great write up in their AFD supporting snow in the morning, sleet early afternoon, then freezing rain takes over. Snow and sleet also for areas outside of the mountains. Stars will have to allign of course with the radar trends. 

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I'm not sure if this will have any implications on what might happen tomorrow, but I was forecast to be somewhere near 37 today; only managed 34.4. Currently 33.9 with a dp of 10. My highest temp all week has only been 36.4 yesterday, and coldest was 7.9 on the 2nd; everything is basically frozen, so I'm sure it will take some things outside to warm above freezing even when the actual air temp goes above.

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15 minutes ago, Lookout said:

yep...although  it won't be a big total precip maker, it sure isn't going to take much to make the roads a mess.  Even prolonged freezing drizzle could cause some serious issues with temps way down in the 20s and a frozen ground. 

fwiw, the euro is quite a bit wetter than other runs and models...shows as much as 0.6 to .8 for atlanta. Probably overdone i'm sure since there is no support for it...although the gfs has been showing a narrow band of heavier totals too...except it has it over central ga. something to watch maybe. 

18z nam is coming in quite a bit wetter...closing in on 0.25 of an inch.  enough to make for some sure enough bad travel conditions in the morning. 

will be interesting to see what the temps do tomorrow regardless. the 18z nam is actually a little warmer...retreating subfreezing temps into northeast ga by afternoon...but with steady precip, it's doubtful. regardless, enough falls in the morning that it's close to warning criteria for western parts. 

 

 

This is one of the times where I wish we would get more or nothing lol. More it would be clear - but just a little wont really look all that bad but could make driving pretty horrendous. A couple of years ago we had less than a tenth inch of ice and the roads were undriveable

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31 minutes ago, calculus1 said:

The models have been quite anemic with regards to precipitation tomrorow for WNC, but NWS GSP just hoisted WWAs for a good chunk of the area.  This may be one of those cases similar to last weekend in the mountains, where just a fraction of water will cause horrific travel conditions.  Kudos to GSP for going ahead and warning people of this issue.

Yup, better safe than sorry. Last week terrible in Asheville and it was a miniscule glaze. This could be terrible with the morning commute. Glad people are now warned. 

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37 minutes ago, Lookout said:

yep...although  it won't be a big total precip maker, it sure isn't going to take much to make the roads a mess.  Even prolonged freezing drizzle could cause some serious issues with temps way down in the 20s and a frozen ground. 

fwiw, the euro is quite a bit wetter than other runs and models...shows as much as 0.6 to .8 for atlanta. Probably overdone i'm sure since there is no support for it...although the gfs has been showing a narrow band of heavier totals too...except it has it over central ga. something to watch maybe. 

18z nam is coming in quite a bit wetter...closing in on 0.25 of an inch.  enough to make for some sure enough bad travel conditions in the morning. 

will be interesting to see what the temps do tomorrow regardless. the 18z nam is actually a little warmer...retreating subfreezing temps into northeast ga by afternoon...but with steady precip, it's doubtful. regardless, enough falls in the morning that it's close to warning criteria for western parts. 

 

 

Most of the ATL precip looks too late too me.  They’ll be above freeezing by 16Z probably maybe even slightly earlier as that wedge is fairly malpositioned.  The threat for the ATL metro may be more 11-14Z before any of the real precip arrives if they drizzle out of the stratus deck

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16 minutes ago, SnowGoose69 said:

Most of the ATL precip looks too late too me.  They’ll be above freeezing by 16Z probably maybe even slightly earlier as that wedge is fairly malpositioned.  The threat for the ATL metro may be more 11-14Z before any of the real precip arrives if they drizzle out of the stratus deck

Those temps wouldn't rise nearly as fast as the nam is showing if precip is that steady...especially north and east burbs and northeast. Seen this way too many times with models, even with a stale airmass, no CAA, latent heat release, strong WAA aloft,  and only a residual cold pool, always show warming far too fast. In fact, in most  situations similar to this one.... the initial temps/wetbulbs are warmer than what we will have tomorrow . It's actually pretty rare to see precip falling into an airmass that is already in the mid to upper 20s before anything falls. 

My doubt lies in the fact it has that much precip though....not much support out there for those amounts other than the euro. 3km nam is a lot drier (although much wetter than prior runs) and keeps most of it north of atlanta to athens. Temps will be very slow to rise tomorrow for many areas unless there is no precip at all. 

 

 

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18 minutes ago, Lookout said:

Those temps wouldn't rise nearly as fast as the nam is showing if precip is that steady...especially north and east burbs and northeast. Seen this way too many times with models, even with a stale airmass, no CAA, latent heat release, strong WAA aloft,  and only a residual cold pool, always show warming far too fast. In fact, in most  situations similar to this one.... the initial temps/wetbulbs are warmer than what we will have tomorrow . It's actually pretty rare to see precip falling into an airmass that is already in the mid to upper 20s before anything falls. 

My doubt lies in the fact it has that much precip though....not much support out there for those amounts other than the euro. 3km nam is a lot drier (although much wetter than prior runs) and keeps most of it north of atlanta to athens. Temps will be very slow to rise tomorrow for many areas unless there is no precip at all. 

 

 

100% agree Lookout. ATL always has a tendency to rise above freezing even with drizzle or something falling, whereas the NE suburbs over to Athens and up to Gainesville and onward will stay put. IF we can get precip to fall early enough (even as virga) that will still strengthen a mesoscale in-situ wedge and lock it in place, and once that happens it's very hard for anything to erode it.

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