Winter Storm 1/6 - 1/8, 2017

[griteater]

Yeah Euro looks similar to other models with 850 0 deg line...it jerks it north there near Raleigh and just to the E and NE of Raleigh too, before collapsing back south

[The Alchemist]

More lightning in LA as storms move through New Orleans...  Is that a signal of increased strength?  Is the low located about where the morning GFS/Nam said it should be?

[PackGrad05]

I mentioned on Monday that Wake county would be the dividing line.  Hard to go against CLIMO!

 

I'm on the southern edge of the county, but 2 inches is a good snow anyway!!!  Hard to get 2"

[FallsLake]

5 minutes ago, DopplerWx said:

12" for rdu on the euro. sharp cutoff with 2" on the southern portion of the county.

Not 2", looks more like ~4" for CR. Probably a lot of sleet; in which that would be impressive.  

[mackerel_sky]

2 minutes ago, DopplerWx said:

nc snow totals

Think the Euro is off!? All the warm nose talk around GSP, and this has the highest totals right on 85 and a little south and not much towards Travelers Rest, about 2-3" there and 7+ for mby! That's why you use short range modeling now, correct?

[NorthGaWinter]

5 minutes ago, DopplerWx said:

nc snow totals

Can you post the map for north ga?

[phil882]

5 minutes ago, griteater said:

Yeah Euro looks similar to other models with 850 0 deg line...it jerks it north there near Raleigh and just to the E and NE of Raleigh too, before collapsing back south

Careful though... because upstream obs show that the warm nose is actually strongest a little bit above 850-hPa which also is showing up on the forecast HRRR soundings near Raleigh overnight. I fear that a lot of the snow in the Euro Snowfall maps may actually be heavy sleet...

[strongwxnc]

1 minute ago, FallsLake said:

Not 2", looks more like ~4" for CR. Probably a lot of sleet; in which that would be impressive.  

I've had 4" of IP before. So crazy to be outside as it pours down. Really cool to go through. 

[SN_Lover]

7 minutes ago, The Alchemist said:

More lightning in LA as storms move through New Orleans...  Is that a signal of increased strength?  Is the low located about where the morning GFS/Nam said it should be?

thats not good. south robbing moisture to the north  pray im wrong tho. 

[griteater]

3 minutes ago, phil882 said:

Careful though... because upstream obs show that the warm nose is actually strongest a little bit above 850-hPa which also is showing up on the forecast HRRR soundings near Raleigh overnight. I fear that a lot of the snow in the Euro Snowfall maps may actually be heavy sleet...

Yep Phil, thanks, we talked earlier about how the warm nose is usually strongest above 850.  Here's the Euro animation FWIW...

 

[FallsLake]

1 minute ago, SN_Lover said:

thats not good. south robbing moisture to the north  pray im wrong tho. 

Might have already been discussed but I think it matters how the storm bands are oriented. Top forward is suppose to be good, top back is bad. Somebody else is that right. 

[Cold Rain]

6 minutes ago, phil882 said:

Careful though... because upstream obs show that the warm nose is actually strongest a little bit above 850-hPa which also is showing up on the forecast HRRR soundings near Raleigh overnight. I fear that a lot of the snow in the Euro Snowfall maps may actually be heavy sleet...

But the GFS gives Wake Forest 12" of snow, so the warm nose can't possibly be that strong or likely!

As always, thanks for your insight, Phil.

[The Alchemist]

2 minutes ago, SN_Lover said:

thats not good. south robbing moisture to the north  pray im wrong tho. 

it is not a big line of storms, broken up, but there is some lift occurring down at the coast...  Didn't know if that was just ahead of the low, or not really related to it..

[LovingGulfLows]

Looking at the current 925s, it looks colder than modeled.

[Cold Rain]

A big, organized band of storms racing out ahead of the system is bad.  A slow-moving band or organized convection, moving in concert with the main system, can enhance moisture transport, if memory serves.

[RubiksDestroyer]

Here's the EuroWx snowfall map, which considers the proper ratios and stuff:

[FallsLake]

2 minutes ago, Cold Rain said:

A big, organized band of storms racing out ahead of the system is bad.  A slow-moving band or organized convection, moving in concert with the main system, can enhance moisture transport, if memory serves.

Thanks! That sounds right/familiar.  

[phil882]

5 minutes ago, Cold Rain said:

But the GFS gives Wake Forest 12" of snow, so the warm nose can't possibly be that strong or likely!

As always, thanks for your insight, Phil.

Unfortunately the GFS snowfall maps count all frozen precipitation in one bin... so the accumulation using a 10:1 ratio is oftentimes not correct if a significant fraction of the frozen precipitation is sleet or freezing rain. The Euro snowfall maps I think take p-type into account so they would be more accurate, but only if they also have an accurate vertical profile.

Again my concern is that global models don't simulate vertical gradients well, so situations where there are strong inversions (like this event) are likely to be under-represented. That's why we always seemed to get burned with the warm nose in the Carolinas during snowfall events, because the models seldom show how intense the cold air is near the surface, nor how strong the warm air is aloft. The HRRR is noticeably warmer aloft than the ECMWF or GFS, with P-type issues all the way into southern VA (look where the strong bright banding is located).

[griteater]

You never know with the moisture robbing convection stuff, but Miller B's are the ones that really get us with the radar looking great in Montgomery, then morphing into a splotchy mess over NC.  Not really expecting that with this one...expecting a more uniform look on radar

[Cold Rain]

2 minutes ago, phil882 said:

Unfortunately the GFS snowfall maps count all frozen precipitation in one bin... so the accumulation using a 10:1 ratio is oftentimes not correct if a significant fraction of the frozen precipitation is sleet or freezing rain. The Euro snowfall maps I think take p-type into account so they would be more accurate, but only if they also have an accurate vertical profile.

Again my concern is that global models don't simulate vertical gradients well, so situations where there are strong inversions (like this event) are likely to be under-represented. That's why we always seemed to get burned with the warm nose in the Carolinas during snowfall events, because the models seldom show how intense the cold air is near the surface, nor how strong the warm air is aloft. The HRRR is noticeably warmer aloft than the ECMWF or GFS, with P-type issues all the way into southern VA (look where the strong bright banding is located).

Good stuff and makes sense.  I was kidding about the GFS.  I agree with you about the models underestimating warmth aloft.  It happens with virtually every storm here.  Would you expect the freezing rain (if any) to remain south of this area?  I imagine that the bulk of what falls in Raleigh is likely to be sleet.  But it does seem that the IP corridor with this storm is wider than what we usually expect from a Miller A.

[Cold Rain]

5 minutes ago, griteater said:

You never know with the moisture robbing convection stuff, but Miller B's are the ones that really get us with the radar looking great in Montgomery, then morphing into a splotchy mess over NC.  Not really expecting that with this one...expecting a more uniform look on radar

Agreed.  I'm not worried about a few random thunderstorms or even a blob of them down in the deep south right now.

[BornAgain13]

26 minutes ago, DopplerWx said:

nc snow totals

You can add 2" or more to that where the higher ratios are.

[No snow for you]

Just now, odell.moton said:

I got one question and I'll fall back.....does it appear as though Greer area is losing snow due to the rain line moving north.....


Sent from my iPhone using Tapatalk

On the models no. The problem are temps if you want snow. 

[phil882]

18 minutes ago, griteater said:

You never know with the moisture robbing convection stuff, but Miller B's are the ones that really get us with the radar looking great in Montgomery, then morphing into a splotchy mess over NC.  Not really expecting that with this one...expecting a more uniform look on radar

Right now I don't see any indication of upstream convection robbing upstream moisture. That normally occurs when you get strong surface based convection that produces a noticeable bowing segment that propagates well ahead of the frontal boundary. That isn't what is happening over the Gulf of Mexico right now. Almost all of the convection is elevated behind the sfc boundary in the Gulf of Mexico, which means the moisture is feeding into the stratiform precipitation bands that are forming where you have the best frotogenetical lift aloft (which will propagate into GA/NC/SC in the next few hours). All good signs for good precipitation rates so far.

[packbacker]

30 minutes ago, DopplerWx said:

12" for rdu on the euro. sharp cutoff with 2" on the southern portion of the county.

Euro was roughly the same, maybe 10 miles further NW with 850 line.  

For example off EuroWx, which takes into account ratio's with mixing, the best it can.  So you can see the cutoff, Angier is 4" and Fuquay is 11.4".  They are like 15 miles from each other.

Angier - 4" 

Clayton - 4.7"

Fuquay- 11.4" 

Raleigh/Apex/Cary - 11.5" (they were all in this range)

Wake Forest - 12.3"

GSO - 8.5"

INT - 6.9"

KCLT - 8.5"

KAVL - 5.3"

[phil882]

8 minutes ago, Cold Rain said:

Good stuff and makes sense.  I was kidding about the GFS.  I agree with you about the models underestimating warmth aloft.  It happens with virtually every storm here.  Would you expect the freezing rain (if any) to remain south of this area?  I imagine that the bulk of what falls in Raleigh is likely to be sleet.  But it does seem that the IP corridor with this storm is wider than what we usually expect from a Miller A.

Well even though this is a Miller A... its a weak Miller A, & the 850-hPa low is quite a bit detached north from the actual sfc cyclone offshore. That's why there are some warm nose issues, because the 850-hPa low will be moving nearly overhead in the piedmont of NC. I'd expect a decent sleet corridor since the 925hPa low is much further south in SC, which should allow for a cold 925-hPa zone in the -2 to -4C range near Raleigh. 

[JQPublic]

Chatham County Line doing work son!  Good luck to all!

 

[packbacker]

For example...EuroWx has Birmingham as a mix until 2pm then flips them to snow sometime between 2-8pm. 

The 0z Euro run had Birmingham as all rain.

[Cold Rain]

3 minutes ago, phil882 said:

Well even though this is a Miller A... its a weak Miller A, & the 850-hPa low is quite a bit detached north from the actual sfc cyclone offshore. That's why there are some warm nose issues, because the 850-hPa low will be moving nearly overhead in the piedmont of NC. I'd expect a decent sleet corridor since the 925hPa low is much further south in SC, which should allow for a cold 925-hPa zone in the -2 to -4C range near Raleigh. 

Awesome, thank you.  So last question for future learning...if this storm were stronger (let's say it were to bomb out, which it won't...but if it did), would that drag the 850 low farther south in better proximity to the surface cyclone?  I realize that if it were strengthening rapidly, it would gain latitude, in which case all features would eventually be north.  I guess I'm just wondering if it were stronger, would the 850 low be closer to the surface cyclone farther south, keeping our area colder?

[SnowNiner]

Matt East in his video mentioned he thought the 850 line would set up somewhere SW of CLT and NW of the city should stay 90% snow.  Sitting at Mt Island lake, about as far NW Mecklenburg County you can be, I hope that tune stays.  The NW trend can stop now!