January 17th-18th Winter Storm Discussion

[BullCityWx]

I think this ends up being a decent enough run for those lucky enough to live west of 77

[eyewall]

The 12z NAM is perfect if you are looking for a solid rain event. The partials and BL are jut not there as it brings the low more to the north and what little cold air is there swings in on the back end. As we know the cold chasing moisture is a dangerous game and it has to work out absolutely perfectly. Interestingly it is how we ended up with our one token even last year in February in this area.

[calculus1]

I think this ends up being a decent enough run for those lucky enough to live west of 77

 

I hope you're right, but the sounding for hour 60 at Hickory does not look too good.  Hour 66 is not available to me, yet.

 

Date: 60 hour Eta valid 0Z 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   134                                                                 SFC  975   336   3.9   2.7  91  1.3   3.4  18  15 279.1 279.9 277.7 292.1  4.76  2  950   550   2.1   1.3  94  0.8   1.7  19  23 279.3 280.1 277.4 291.5  4.41  3  900   985   0.8   0.0  95  0.7   0.5  16  43 282.3 283.0 278.7 294.2  4.26  4  850  1447   2.7   2.2  97  0.5   2.5  12  32 289.0 289.9 283.0 304.1  5.29  5  800  1935   0.2   0.2 100  0.1   0.2  35  26 291.4 292.3 283.5 305.4  4.84  6  750  2452  -0.5  -0.5 100  0.0  -0.5 102  11 296.0 296.9 285.5 310.5  4.91  7  700  3002  -2.6  -2.6 100  0.0  -2.6 163   9 299.6 300.5 286.5 313.2  4.51  8  650  3587  -5.6  -6.1  96  0.5  -5.8 198  14 302.6 303.3 286.7 314.0  3.72  9  600  4210  -9.8 -10.7  93  0.9 -10.1 192  22 304.8 305.3 286.6 313.6  2.82 10  550  4877 -13.3 -14.4  92  1.1 -13.7 178  29 308.3 308.7 287.3 315.6  2.28 11  500  5597 -17.5 -18.8  89  1.3 -17.9 169  38 311.7 312.0 287.9 317.4  1.73 12  450  6376 -24.0 -27.7  72  3.6 -24.7 166  48 313.0 313.2 287.4 316.0  0.88 13  400  7224 -29.3 -40.2  34 10.9 -30.5 178  60 316.9 316.9 288.1 317.9  0.29 14  350  8169 -33.4 -57.0   8 23.6 -34.8 191  79 323.7 323.7 289.9 323.9  0.05 15  300  9236 -40.5 -64.7   6 24.2 -41.3 197  90 328.3 328.3 291.2 328.4  0.02 16  250 10457 -47.9 -78.1   2 30.2 -48.4 204  87 334.9 334.9 293.0 334.9  0.00 17  200 11904 -54.3 -75.4   6 21.1 -54.6 216  83 346.8 346.8 295.9 346.8  0.01 18  150 13723 -59.3 -72.9  16 13.5 -59.5 230  88 367.8 367.8 300.2 367.9  0.01 19  100 16229 -64.6 -82.1   7 17.5 -64.8 235  76 402.8 402.8 305.6 402.8  0.00TRP                                             0                              WND                                             0                              Sounding variables and indices1000-500 mb thick:      5462.42 mFreezing level:          783.80 mb =  2102.36 m =  6897.43 ftWetbulb zero:            786.09 mb =  2075.30 m =  6808.64 ftPrecipitable water:        0.80 inches

[BullCityWx]

Well, your temps crash somewhere close to 63.

[DaculaWeather]

I hope you're right, but the sounding for hour 60 at Hickory does not look too good.  Hour 66 is not available to me, yet.

 

Date: 60 hour Eta valid 0Z 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   134                                                                 SFC  975   336   3.9   2.7  91  1.3   3.4  18  15 279.1 279.9 277.7 292.1  4.76  2  950   550   2.1   1.3  94  0.8   1.7  19  23 279.3 280.1 277.4 291.5  4.41  3  900   985   0.8   0.0  95  0.7   0.5  16  43 282.3 283.0 278.7 294.2  4.26  4  850  1447   2.7   2.2  97  0.5   2.5  12  32 289.0 289.9 283.0 304.1  5.29  5  800  1935   0.2   0.2 100  0.1   0.2  35  26 291.4 292.3 283.5 305.4  4.84  6  750  2452  -0.5  -0.5 100  0.0  -0.5 102  11 296.0 296.9 285.5 310.5  4.91  7  700  3002  -2.6  -2.6 100  0.0  -2.6 163   9 299.6 300.5 286.5 313.2  4.51  8  650  3587  -5.6  -6.1  96  0.5  -5.8 198  14 302.6 303.3 286.7 314.0  3.72  9  600  4210  -9.8 -10.7  93  0.9 -10.1 192  22 304.8 305.3 286.6 313.6  2.82 10  550  4877 -13.3 -14.4  92  1.1 -13.7 178  29 308.3 308.7 287.3 315.6  2.28 11  500  5597 -17.5 -18.8  89  1.3 -17.9 169  38 311.7 312.0 287.9 317.4  1.73 12  450  6376 -24.0 -27.7  72  3.6 -24.7 166  48 313.0 313.2 287.4 316.0  0.88 13  400  7224 -29.3 -40.2  34 10.9 -30.5 178  60 316.9 316.9 288.1 317.9  0.29 14  350  8169 -33.4 -57.0   8 23.6 -34.8 191  79 323.7 323.7 289.9 323.9  0.05 15  300  9236 -40.5 -64.7   6 24.2 -41.3 197  90 328.3 328.3 291.2 328.4  0.02 16  250 10457 -47.9 -78.1   2 30.2 -48.4 204  87 334.9 334.9 293.0 334.9  0.00 17  200 11904 -54.3 -75.4   6 21.1 -54.6 216  83 346.8 346.8 295.9 346.8  0.01 18  150 13723 -59.3 -72.9  16 13.5 -59.5 230  88 367.8 367.8 300.2 367.9  0.01 19  100 16229 -64.6 -82.1   7 17.5 -64.8 235  76 402.8 402.8 305.6 402.8  0.00TRP                                             0                              WND                                             0                              Sounding variables and indices1000-500 mb thick:      5462.42 mFreezing level:          783.80 mb =  2102.36 m =  6897.43 ftWetbulb zero:            786.09 mb =  2075.30 m =  6808.64 ftPrecipitable water:        0.80 inches

Here are the nomograms for Hickory

http://www.daculaweather.com/nomogram_hky.php

[burgertime]

Sorry I was in a work meeting. This one looks great moisture wise for MBY but as everyone else has noted just a cold rain more than likely. 

[nchighcountrywx]

Verbatim on the untrusty snow charts on the NAM, they show 11 inches of snow in the Smokes around Mount Leconte.

 

Snow tapers off rapidly to the NE with very little making it into counties in the NW North Carolina Mountains

 

[Bevo]

Definitely cannot rule out WNC mountain snow - in fact, I think it's likely. 

 

But I see even less of a chance for some of the spots that were questionable to begin with.  GSP through CLT to be specific.  Temps will be the hurdle they always tend to be, especially with this system.  I still think as I did yesterday that the very northern boundaries of a few SC counties (Oconee, Pickens and maybe Greenville) could see a few flakes, particularly the Table Rock/Caesar's Head areas. 

 

West of I-77 (I think QueenCity may have even pointed this out) is going to be a riddle to the bitter end.  Even if qpf is heavier, the temps look menacing - I'm wondering if a column crash will make any difference outside of elevation.

[strongwxnc]

This is the type of set up whereupon my county gets split in half with the lower getting cold rain and the upper nw getting in on the action . Per this nam run !

I think this ends up being a decent enough run for those lucky enough to live west of 77

[tnweathernut]

Is anyone else not amazed at the precip this is putting out?  3.77 on the NC,SC,GA border from what was suppose to be a "light" event.  Our area has already had 3.4 inches and should get 1-2 more BEFORE this event.  It's shaping up to be a month with MUCH ABOVE normal precipitation here in east TN.

[calculus1]

Here are the nomograms for Hickory

http://www.daculaweather.com/nomogram_hky.php

 

Someone's going to have to give me a lesson on this.  I saw the model underneath this graph which detailed which regions represent which types of precip.  But what do the numbers mean both in the interior of the graph and the ones on the side?

 

[burgertime]

Only saving grace will be if this can keep trending stronger like the NAM is wanting to do. By Thurs morning it might be a two contour low going through SC lol. 

[calculus1]

Someone's going to have to give me a lesson on this.  I saw the model underneath this graph which detailed which regions represent which types of precip.  But what do the numbers mean both in the interior of the graph and the ones on the side?

 

 

Maybe I just figured it out.  Does 18_06 correspond to 1/18/13 at 06Z?  So, what precip does fall during that period (hour 66 of the NAM) would be measurable snow with rain because of the quadrant it is located in?

[DaculaWeather]

The numbers inside the graph are dates and model runs.  The numbers to the right are thickness levels for each column. It order to have winter precip, the thickness needs to drop to a certain level. The graph is just depicting those numbers in areas that are mapped out to let you know specifically what may happen.

[DaculaWeather]

Maybe I just figured it out.  Does 18_06 correspond to 1/18/13 at 06Z?  So, what precip does fall during that period (hour 66 of the NAM) would be measurable snow with rain because of the quadrant it is located in?

Correct

[Stovepipe]

Those of us in east TN have to hope the NAM is on to something.  That's two runs in a row with significant snow verbatim for the central valley.

 

 

Of course, if it keeps trending eastward (which is likely), no dice.

[nchighcountrywx]

Someone's going to have to give me a lesson on this.  I saw the model underneath this graph which detailed which regions represent which types of precip.  But what do the numbers mean both in the interior of the graph and the ones on the side?

 

 

Here you go on the Winter Storm Nomograms

 

CreateNomogramProcedure.doc

CreateNomogramProcedure.doc

[burgertime]

This should help

 

 

That's really hard to read 

[Tacoma]

Verbatim on the untrusty snow charts on the NAM, they show 11 inches of snow in the Smokes around Mount Leconte.

 

Snow tapers off rapidly to the NE with very little making it into counties in the NW North Carolina Mountains

 

buncombe county and west to tennessee line looks good as well as extreme east tenneessee this may still trend east a little yet though

[FoothillsNC]

The NAM's temp profiles will be wrong, and it will catch up soon. You'll see that once it adjusts to the core being strong like its 5h shows. I see this with most upper lows regarding NAM. What I question is the strength and orientation of the closed vort....its very healthy and takes the right path to get folks under and just northwest of it to go from rain to snow, since thats where the cold will work on dynamic cooling. I think folks forgot what upper lows always end up doing...and that's exactly that....go from rain to snow or sleet, in a flash, even when temps are 39 or 40. Accumulations will be tough since the warm ground and probably surface air temps going no lower than 33 other than the mountains on Thursday night, but this would be a case of snow falling, but only sticking to bushes and car tops briefly. Different story in the mountains of TN and NC I think, and maybe southwest VA if the moisture gets there. Strong comma head rates could nail that area and the rates would overcome the warm ground for a few hours, so even though snow melts underneath continuously, the rates will allow a few inches accumulation anyway, just because of some serious rates for a few hours.  Usually thundersnow in the nw side as well for some lucky folks...could be anywhere northwest of the vort track, from north alabama, n. Ga e TN, anywhere NC, possibly n SC.  This is a fast mover and won't last long, but like usual upper lows have surprises and are one of the funnest of all things to forecast in weather....finally something to track, winter-wise.

[buckeyefan1]

That's really hard to read 

 

 For some reason it resized the picture so only those with bifocals could see it properly     

 

Anywho....the nam dumps some much needed rainfall imby, let's hope Goofy continues the trend  

[BullCityWx]

One of the storms on the CIPS guidance is 2/19/1999. Does anyone remember that event? The evolution of this one would be quite similar.

[BullCityWx]

NAM extracted data gives Gastonia 3.9" of snow:

http://68.226.77.253/text/NAMSFC/NAM_kakh.txt

[weatherheels]

Just looking at the snow it dropped in NC it would appear to have been a clipper... but that could be completely wrong. 

One of the storms on the CIPS guidance is 2/19/1999. Does anyone remember that event? The evolution of this one would be quite similar.

[Met1985]

The NAM's temp profiles will be wrong, and it will catch up soon. You'll see that once it adjusts to the core being strong like its 5h shows. I see this with most upper lows regarding NAM. What I question is the strength and orientation of the closed vort....its very healthy and takes the right path to get folks under and just northwest of it to go from rain to snow, since thats where the cold will work on dynamic cooling. I think folks forgot what upper lows always end up doing...and that's exactly that....go from rain to snow or sleet, in a flash, even when temps are 39 or 40. Accumulations will be tough since the warm ground and probably surface air temps going no lower than 33 other than the mountains on Thursday night, but this would be a case of snow falling, but only sticking to bushes and car tops briefly. Different story in the mountains of TN and NC I think, and maybe southwest VA if the moisture gets there. Strong comma head rates could nail that area and the rates would overcome the warm ground for a few hours, so even though snow melts underneath continuously, the rates will allow a few inches accumulation anyway, just because of some serious rates for a few hours.  Usually thundersnow in the nw side as well for some lucky folks...could be anywhere northwest of the vort track, from north alabama, n. Ga e TN, anywhere NC, possibly n SC.  This is a fast mover and won't last long, but like usual upper lows have surprises and are one of the funnest of all things to forecast in weather....finally something to track, winter-wise.

Thanks Robert for posting.

[DaculaWeather]

The NAM's temp profiles will be wrong, and it will catch up soon. You'll see that once it adjusts to the core being strong like its 5h shows. I see this with most upper lows regarding NAM. What I question is the strength and orientation of the closed vort....its very healthy and takes the right path to get folks under and just northwest of it to go from rain to snow, since thats where the cold will work on dynamic cooling. I think folks forgot what upper lows always end up doing...and that's exactly that....go from rain to snow or sleet, in a flash, even when temps are 39 or 40. Accumulations will be tough since the warm ground and probably surface air temps going no lower than 33 other than the mountains on Thursday night, but this would be a case of snow falling, but only sticking to bushes and car tops briefly. Different story in the mountains of TN and NC I think, and maybe southwest VA if the moisture gets there. Strong comma head rates could nail that area and the rates would overcome the warm ground for a few hours, so even though snow melts underneath continuously, the rates will allow a few inches accumulation anyway, just because of some serious rates for a few hours.  Usually thundersnow in the nw side as well for some lucky folks...could be anywhere northwest of the vort track, from north alabama, n. Ga e TN, anywhere NC, possibly n SC.  This is a fast mover and won't last long, but like usual upper lows have surprises and are one of the funnest of all things to forecast in weather....finally something to track, winter-wise.

 

Thanks Robert!

 

Guys, in regards to those nonograms, also refer to the graph below the charts, it's interactive and tells you almost everything you need to know.

[deltadog03]

I am just glad that the rain is going to return.  BTW, I REALLY think the big winner could be the northern upstate of SC.  *Higher Country*

[burgertime]

12z GFS nowhere even close outside of the mountains verbatim on temps. 

[Tacoma]

Just looking at the snow it dropped in NC it would appear to have been a clipper... but that could be completely wrong. 

the storm thursday night seems to be a little more south than the one in 1999. not sure the nothern mtns. see much unless this trends a little more north. I think all the mtns will be cold enough for snow just depending how far north the moisture gets, maybe the nc va line?

[tnweathernut]

Trends really seem to paint mucho qpf for an area centered around the southern apps or just south of there...........

 

It would have been nice to see a vort diving down the front range of the rockies in behind this potent southern shortwave.  Bombgenesis would have been a wonderful thing to watch with a widespread snow and ice event for many.