January 17th-18th Winter Storm Discussion

[HKY18]

the 11z rap has a pretty sick def band over all of western nc for many hours. Just based on 850 temps at least .75 of that is snow, and that's being really conservative it actually show up to 1.25-1.50 after 850s crash.

[NEGa]

Yep...funny how that upper low just suddenly turns ne just in time to screw north ga (for the most part) then turns back east again after it passes? So you have MS, AL, far upstate SC, and most of NC getting hit pretty good (well hammered in NC) while we have our usual screwjob. Only hope we have some some sort of convection underneath or near the upper low before the moisture moves out and that's heavy enough to overcome that low leel warm air..for a brief snow shower or mix.  That's about it. The upper low, 850mb low, etc is just too far north..we need it in south ga or something). . Hard pill to swallow watching it unfold like that. 

Amazing isn't it lol. N ga can get screwed in almost any set up. Love all the advisories and warnings in n ga and then a forecast that doesn't really call for snow or accumulating snow sigh. This set up doesn't bode well for ne ga - most of snow stops about a county or two away

[RaleighWx]

My morning update:

 

http://www.examiner.com/article/quick-hitting-snow-likely-to-strike-southeast-this-afternoon-and-tonight

 

 

[oconeexman]

Amazing isn't it lol. N ga can get screwed in almost any set up. Love all the advisories and warnings in n ga and then a forecast that doesn't really call for snow or accumulating snow sigh. This set up doesn't bode well for ne ga - most of snow stops about a county or two away

You can include NW SC in the usual screwjob as well! Painful to watch!!

[rawlee]

My morning update:

 

http://www.examiner.com/article/quick-hitting-snow-likely-to-strike-southeast-this-afternoon-and-tonight

 

Thanks Allan, let's bring this puppy home!

[HKY_WX]

Latest run of the RAP seems to only hold the 500 mb low closed until it gets to roughly Charlotte.  It then opens up for it's progression eastward.

 

 

Weren't some of the models last night keeping this low closed all the way to the coast?  I'm not sure of all the implications, but I believe the system would not be as strong if it opens up sooner.  Thoughts?

 

Here's the SE view from one forecast run earlier (10Z).

 

It's prob not going to make a huge difference at this point in the game. Too be honest, seeing it maintain a closed off contour all the way to  central/eastern NC is very rare for these cutoffs over the southeast. Usually they open up sooner. That's why I think we're going to see a very distinct band of heavy snow tonight over NC.

[Wow]

Latest run of the RAP seems to only hold the 500 mb low closed until it gets to roughly Charlotte.  It then opens up for it's progression eastward.

 

 

 

Weren't some of the models last night keeping this low closed all the way to the coast?  I'm not sure of all the implications, but I believe the system would not be as strong if it opens up sooner.  Thoughts?

 

Here's the SE view from one forecast run earlier (10Z).

 

I noticed this as well with the increased interaction with energy from the northern stream.  But on the surface, there's not much change. In fact, it's probably trending a bit stronger and colder.

[HKY_WX]

The warm ground issue would not be a problem at all in those rates.  I think the warm ground issue is entirely over-stated in events like these.  Yes, the initial snow will melt but if your snowing 1-2 inches per hour on ground with snow melting, eventually it will stick in a hurry.  Speaking from experience, on November 7, we were forecasting light accums across the tri-state (northeast around NYC), and some places ended up with over a foot.  It even accumulated to 6 inches at my apartment on Long Island.  We thought warm ground would limit accums.  Another thing, it will be snowing when its dark.  No solar radiation to effect the ground temps. Now if it the snow is very light, then yeah that will be a issue, but with everything we are seeing, the rates will be more than sufficient.

 

The warm ground issue would not be a problem at all in those rates.  I think the warm ground issue is entirely over-stated in events like these.  Yes, the initial snow will melt but if your snowing 1-2 inches per hour on ground with snow melting, eventually it will stick in a hurry.  Speaking from experience, on November 7, we were forecasting light accums across the tri-state (northeast around NYC), and some places ended up with over a foot.  It even accumulated to 6 inches at my apartment on Long Island.  We thought warm ground would limit accums.  Another thing, it will be snowing when its dark.  No solar radiation to effect the ground temps. Now if it the snow is very light, then yeah that will be a issue, but with everything we are seeing, the rates will be more than sufficient.

I agree. Thanks for the input! With this being at night, it's a nice little bonus as far as accumulations is concerned.

[beanskip]

I know it's nowcasting time yada yada, but the difference between the NAM and GFS soundings is pretty amazing at this short time frame.

 

If the NAM is right it's going to be

If the GFS is right it's going to be

 

6z NAM at 21 hours for Shelby:

PRESS HGT(MSL) TEMP DEW PT  WND DIR  WND SPD
HPA       M      C     C       DEG     M/S 
E = Estimated Surface Height

  PRESS HGT(MSL) TEMP DEW PT  WND DIR  WND SPD
HPA       M      C     C       DEG     M/S 
E = Estimated Surface Height

  989.   250.    0.5    0.2     4.0     5.3
  975.   364.    0.0    0.0    12.3     9.5
  950.   573.    0.0    0.1    22.9    16.2
  925.   786.   -0.3   -0.4    31.3    21.2
  900.  1005.   -0.9   -1.1    31.7    24.1
  875.  1229.   -2.2   -2.5    27.9    24.4
  850.  1459.   -2.7   -3.0    25.1    24.5
  825.  1696.   -3.0   -3.3    23.1    23.2
  800.  1940.   -4.0   -4.4    23.4    22.5
  775.  2190.   -4.2   -4.4    25.1    19.6
  750.  2448.   -4.6   -5.0    13.7    16.1
  725.  2714.   -6.6   -7.0    21.7    17.6
  700.  2988.   -7.8   -8.1    37.1    16.1
  650.  3562.   -9.8  -10.0    58.2     9.4
  600.  4176.  -12.9  -13.8   345.6     5.8
  550.  4832.  -18.9  -19.9   335.8     4.0
  500.  5533.  -24.4  -29.6    12.1     2.2
  450.  6295.  -26.9  -43.7   266.3     4.4
  400.  7139.  -30.1  -63.2   240.5    11.3
  350.  8082.  -32.6  -63.8   237.3    18.6
  300.  9159.  -37.6  -67.0   234.1    23.6
  250. 10395.  -44.1  -69.0   238.4    27.9
  200. 11875.  -49.9  -75.0   238.4    29.6
  150. 13722.  -56.7  -75.1   245.0    40.4
  100. 16250.  -63.4  -85.7   243.0    40.9
   50. 20438.  -67.9  -91.2   237.9    25.1
 
 

 

6z GFS at 21 hours for Shelby

 

 

PRESS HGT(MSL) TEMP DEW PT  WND DIR  WND SPD
HPA       M      C     C       DEG     M/S 
E = Estimated Surface Height

  978.   331.    2.8    2.3   349.4     4.8
  975.   362.    3.3    1.5   356.6     8.4
  950.   572.    2.3    0.2     5.1    12.5
  925.   787.    1.1   -0.8    13.8    15.7
  900.  1007.   -0.4   -1.6    17.7    17.9
  850.  1462.   -3.1   -3.7    19.6    22.5
  800.  1941.   -4.6   -6.3    16.8    24.9
  750.  2448.   -5.2   -7.1    13.2    23.8
  700.  2989.   -6.8   -7.9    10.2    21.1
  650.  3564.   -9.8  -10.6    13.7    18.7
  600.  4177.  -13.9  -14.4    12.2    14.6
  550.  4833.  -18.0  -18.4   341.8    12.3
  500.  5539.  -22.6  -26.0   325.7    12.7
  450.  6303.  -27.5  -32.9   316.4     9.6
  400.  7145.  -29.9  -45.2   264.9     9.3
  350.  8091.  -32.8  -53.5   250.8    17.6
  300.  9166.  -37.0  -75.9   249.8    26.4
  250. 10408.  -43.9  -72.3   250.2    33.2
  200. 11881.  -50.9  -70.8   246.8    33.5
  150. 13723.  -56.5  -69.9   238.0    37.6
  100. 16248.  -62.8  -78.5   245.7    36.2
   50. 20460.  -66.6  -87.8   245.8    20.6
   20. 26056.  -59.2 -273.1   239.5    12.6
 

[strongwxnc]

Same boat here skip! Going to be close!

I know it's nowcasting time yada yada, but the difference between the NAM and GFS soundings is pretty amazing at this short time frame.

If the NAM is right it's going to be

If the GFS is right it's going to be

6z NAM at 21 hours for Shelby:

PRESS HGT(MSL) TEMP DEW PT WND DIR WND SPD

HPA M C C DEG M/S

E = Estimated Surface Height

PRESS HGT(MSL) TEMP DEW PT WND DIR WND SPD

HPA M C C DEG M/S

E = Estimated Surface Height

989. 250. 0.5 0.2 4.0 5.3

975. 364. 0.0 0.0 12.3 9.5

950. 573. 0.0 0.1 22.9 16.2

925. 786. -0.3 -0.4 31.3 21.2

900. 1005. -0.9 -1.1 31.7 24.1

875. 1229. -2.2 -2.5 27.9 24.4

850. 1459. -2.7 -3.0 25.1 24.5

825. 1696. -3.0 -3.3 23.1 23.2

800. 1940. -4.0 -4.4 23.4 22.5

775. 2190. -4.2 -4.4 25.1 19.6

750. 2448. -4.6 -5.0 13.7 16.1

725. 2714. -6.6 -7.0 21.7 17.6

700. 2988. -7.8 -8.1 37.1 16.1

650. 3562. -9.8 -10.0 58.2 9.4

600. 4176. -12.9 -13.8 345.6 5.8

550. 4832. -18.9 -19.9 335.8 4.0

500. 5533. -24.4 -29.6 12.1 2.2

450. 6295. -26.9 -43.7 266.3 4.4

400. 7139. -30.1 -63.2 240.5 11.3

350. 8082. -32.6 -63.8 237.3 18.6

300. 9159. -37.6 -67.0 234.1 23.6

250. 10395. -44.1 -69.0 238.4 27.9

200. 11875. -49.9 -75.0 238.4 29.6

150. 13722. -56.7 -75.1 245.0 40.4

100. 16250. -63.4 -85.7 243.0 40.9

50. 20438. -67.9 -91.2 237.9 25.1

6z GFS at 21 hours for Shelby

PRESS HGT(MSL) TEMP DEW PT WND DIR WND SPD

HPA M C C DEG M/S

E = Estimated Surface Height

978. 331. 2.8 2.3 349.4 4.8

975. 362. 3.3 1.5 356.6 8.4

950. 572. 2.3 0.2 5.1 12.5

925. 787. 1.1 -0.8 13.8 15.7

900. 1007. -0.4 -1.6 17.7 17.9

850. 1462. -3.1 -3.7 19.6 22.5

800. 1941. -4.6 -6.3 16.8 24.9

750. 2448. -5.2 -7.1 13.2 23.8

700. 2989. -6.8 -7.9 10.2 21.1

650. 3564. -9.8 -10.6 13.7 18.7

600. 4177. -13.9 -14.4 12.2 14.6

550. 4833. -18.0 -18.4 341.8 12.3

500. 5539. -22.6 -26.0 325.7 12.7

450. 6303. -27.5 -32.9 316.4 9.6

400. 7145. -29.9 -45.2 264.9 9.3

350. 8091. -32.8 -53.5 250.8 17.6

300. 9166. -37.0 -75.9 249.8 26.4

250. 10408. -43.9 -72.3 250.2 33.2

200. 11881. -50.9 -70.8 246.8 33.5

150. 13723. -56.5 -69.9 238.0 37.6

100. 16248. -62.8 -78.5 245.7 36.2

50. 20460. -66.6 -87.8 245.8 20.6

20. 26056. -59.2 -273.1 239.5 12.6

[Moose4]

My morning update:

 

http://www.examiner.com/article/quick-hitting-snow-likely-to-strike-southeast-this-afternoon-and-tonight

Thanks, great update. It's going to be an interesting evening here on the Cabarrus/Rowan county line, it looks like. I haven't been following the discussion over here so my jaw hit the floor when I pulled up the NWS website this morning and saw them forecasting 3-5" for Kannapolis.

[calculus1]

It's prob not going to make a huge difference at this point in the game. Too be honest, seeing it maintain a closed off contour all the way to  central/eastern NC is very rare for these cutoffs over the southeast. Usually they open up sooner. That's why I think we're going to see a very distinct band of heavy snow tonight over NC.

 

 

I noticed this as well with the increased interaction with energy from the northern stream.  But on the surface, there's not much change. In fact, it's probably trending a bit stronger and colder.

 

Thank you both for the responses.  Here's a Hickory sounding near the end of the event on the 06Z NAM.  There's a brief warm nose that seems to sneak in around 850 mb.  The wet-bulb is below zero, but there is very little precipitable water left in the atmosphere at this point.  Thus, I suppose this is where NWS is getting the idea of a light glaze of freezing rain at the end.  If the precip rates were hard enough, it would still be snow, but this doesn't appear to be so at this time.

 

Date: 27 hour Eta valid 9Z FRI 18 JAN 13Station: KHKYLatitude:   35.73Longitude: -81.38-------------------------------------------------------------------------------LEV PRES  HGHT  TEMP  DEWP  RH  DD   WETB DIR SPD THETA THE-V THE-W THE-E   W     mb     m     C     C    %   C     C  deg knt   K     K     K     K    g/kg-------------------------------------------------------------------------------  0 1000   203                                                                 SFC  984   336  -0.5  -5.3  70  4.7  -2.2 326   8 273.9 274.3 271.8 281.1  2.62  2  950   614  -0.5  -7.8  58  7.3  -3.0 335  22 276.7 277.1 272.8 282.9  2.23  3  900  1046   0.3 -17.2  26 17.4  -4.7 343  36 281.8 282.0 274.0 285.1  1.10  4  850  1504   0.5 -26.8  11 27.3  -5.8 346  35 286.6 286.7 275.7 288.2  0.50  5  800  1988  -1.6 -33.8   6 32.2  -7.8 347  36 289.5 289.5 276.9 290.4  0.28  6  750  2498  -4.1 -35.6   7 31.5  -9.8 349  33 292.2 292.2 278.2 293.0  0.25  7  700  3039  -6.0 -35.3   8 29.2 -11.3 344  35 295.8 295.9 279.9 296.7  0.27  8  650  3618  -7.1 -35.2   9 28.0 -12.3 331  40 300.9 301.0 282.1 301.9  0.30  9  600  4237  -9.8 -34.6  11 24.8 -14.4 327  47 304.8 304.9 283.8 306.0  0.34 10  550  4904 -13.3 -42.0   7 28.7 -17.5 316  44 308.3 308.3 284.9 308.9  0.17 11  500  5622 -18.3 -51.8   4 33.6 -21.7 297  43 310.8 310.8 285.7 311.0  0.06 12  450  6399 -23.8 -58.1   3 34.3 -26.3 301  45 313.3 313.3 286.5 313.4  0.03 13  400  7248 -29.4 -63.4   2 34.0 -31.3 296  45 316.7 316.7 287.7 316.8  0.02 14  350  8189 -35.6 -66.2   3 30.6 -36.8 283  51 320.8 320.8 289.0 320.8  0.01 15  300  9244 -43.6 -65.6   7 22.0 -44.2 267  58 323.9 323.9 290.0 324.0  0.02 16  250 10447 -51.5                      260  65 329.5                         17  200 11873 -55.8                      256  72 344.4                         18  150 13685 -59.5                      249  72 367.5                         19  100 16190 -64.9                      244  69 402.4                        TRP                                             0                              WND                                             0                              Sounding variables and indices1000-500 mb thick:      5418.32 mFreezing level:      Surface below freezingFreezing level:          916.86 mb =   900.26 m =  2953.58 ftFreezing level:          838.49 mb =  1615.27 m =  5299.37 ftWetbulb zero:        Below ground

[packfan98]

As I have looked at some of the animated depictions this morning, I do have one concern that lingers in the back of my mind for areas east of the mountains:

 

When will the changeover actually happen?

 

It looks that it coincides with some of the heavy radar returns.  I know that we often wait, and wait,....and wait for the change to snow and us weenies freak out in the agony of waiting.  However, sometimes there is a warm nose that will delay the changeover. I hope that the changeover happens just BEFORE the good banding and precip rates hit.  I would hate to have a swing and a miss!  I do think that my area could see anywhere from a sloppy inch to as much as 6 inches (max) if we get under those 40 and even 45 dzb returns with some thundersnow.  If that happens, it will seem more like a squall line than a deformation band!

 

Anyway, I'm hoping for the Thrill of Victory instead of the Agony of Defeat.  I think regardless there will be no school in the triad areas tomorrow (black ice).

[Chattownsnow]

latest RAP run showing isolated spots of .5 in/hr precipitation rates into WNC. and that's all snow. just incredible

[burgertime]

Well one thing is for sure as Allan pointed out somewhere around CLT there will be a sharp cutoff of accumulating snow. RAP seems to be indicating this as well. 

[HurricaneTracker]

Not sure if it has been posted yet...but the Storm Prediction Center has outlined wNC and parts of upstate SC for thunder!

 

http://www.spc.noaa.gov/products/outlook/day1otlk.html

[burgertime]

Not sure if it has been posted yet...but the Storm Prediction Center has outlined wNC and parts of upstate SC for thunder!

 

http://www.spc.noaa.gov/products/outlook/day1otlk.html

 

Wow nice, good luck up in AVL! I'm hoping I can get under some of that action. 

[chapelhillwx]

Over the last couple runs, the RAP model has indicated a band with 0.25-0.5" QPF in an hour moving from WNC through the Triangle.Changeover looks to be around 9PM.

[LovingGulfLows]

Yeah, i don't really see that band of snow hitting Atlanta at all lol. It already looks like it[s moving to the northeast and will clip or completely miss the area. I guess we deserve it after getting hit very hard in March of 2009 in that cold core low. Oh well, hopefully this isn't the last chance we have at snow here this winter. Still would like to see some accum. snow before winter is over. Good luck in N Al,, NC, and Upstate SC!

[Wow]

Well one thing is for sure as Allan pointed out somewhere around CLT there will be a sharp cutoff of accumulating snow. RAP seems to be indicating this as well. 

 

Just south of the deformation band, indeed.  The band seems to set up, per the RAP, in a line from Roxboro-Statesville-Hendersonville.

[strongwxnc]

Thanks for posting ! I am right In the middle of that bubble !!!!

Bring it!

Not sure if it has been posted yet...but the Storm Prediction Center has outlined wNC and parts of upstate SC for thunder!

http://www.spc.noaa.gov/products/outlook/day1otlk.html

[Lookout]

Amazing isn't it lol. N ga can get screwed in almost any set up. Love all the advisories and warnings in n ga and then a forecast that doesn't really call for snow or accumulating snow sigh. This set up doesn't bode well for ne ga - most of snow stops about a county or two away

 

The good news for you is you have some elevation so you are more likely to get something out of it. nam/rap show a back end precip band...for several hours, which at your elevation probably means at least a few hours of snow and I wouldn't be surprised to see you get some accumulation. 

 

 For lower elevations, it will take some heavy/convective precip to get anything to the surface. Although the models like to show what appears to be too warm of boundary layer temps, if the precip is heavy/convective enough it could happen. Models have a hard time dealing with such micro situations like that and It is possible given how cold it will be aloft.  700mb temps are as cold as -10. Won't amount to much and would only be a novelty...if it happens at all.

 

But yeah, it's just amazing how this low, which starts out GREAT as far as how far south it is,  if you wanted snow for us, turns NE, we get warmer air in the boundary layer as a result which in turns screws most of us (ONLY place in the se mind you),  then goes back east to hammer NC. I agree with robert/foothills and the others that the snow rates will likely be very intense for a while in NC and the accumulations will likely be surprising to many folks. Doesn't  matter if it snows for just 6 hours if you are dealing with 2 inch or higher snow rates.

 

 

You can include NW SC in the usual screwjob as well! Painful to watch!!

 

You have a better chance than us, thats for sure. You are further north of the 500/850mb/700mb low and  and per rap the precip band, which looks heavy (0.25 to 0.50 in just a few hours)  So I think the upstate or parts of it, especially near the nc line likely sees snow, maybe even  some accumulation. Meanwhile, Ga is stuck with the center of the  bubble of warm air in the boundary layer which means, other than what I mentioned above, screws us.

[chapelhillwx]

12z NAM snowfall

[calculus1]

12z NAM snowfall

 

WOW!  That snow shadow continues to be modeled strongly in the foothills of NC.  You keep hoping the next run will take it away, but it doesn't.  The GFS has lost that shadow, but isn't the NAM run at higher resolution than the GFS?  Of course, the 4km NAM is at even higher resolution.  I think I would have to lean closer to the NAM than the GFS at this point too, inside 24 hours.

[Lookout]

Yeah, i don't really see that band of snow hitting Atlanta at all lol. It already looks like it[s moving to the northeast and will clip or completely miss the area. I guess we deserve it after getting hit very hard in March of 2009 in that cold core low. Oh well, hopefully this isn't the last chance we have at snow here this winter. Still would like to see some accum. snow before winter is over. Good luck in N Al,, NC, and Upstate SC!

 

It's going to be painful and frustrating indeed to see the snow in ms/al suddenly decrease as it nears georgia (if not disappear except isolated pockets)  only to see it reform east of us...with nc seeing rates that could be unbelievable. Sickening but typical of living in north Ga.

[SnowGoose69]

It's going to be painful and frustrating indeed to see the snow in ms/al suddenly decrease as it nears georgia (if not disappear except isolated pockets)  only to see it reform east of us...with nc seeing rates that could be unbelievable. Sickening but typical of living in north Ga.

The 12Z NAM appears to have gone further north...the 700 low tracks right over ATL.

[eyewall]

12z NAM snowfall

 

This would be consistent with NWS saying Danville, VA through the Triad would be a good spot. I am debating a trip from Carrboro to GSO.

[Wow]

The 12Z NAM appears to have gone further north...the 700 low tracks right over ATL.

 

A hair north, similar to what the RAP has trended to.

[Isopycnic]

12z NAM snowfall

That follows the typical NW of RAH "snowline" nicely. 

[Wow]

Gonna be a lot a precip falling. As much as 2" QPF over some areas

 

Half of this is  rain keep in mind