January Pattern and Storm Discussion II

[Cold Rain]

Looks a little cooler than the two previous runs, but there doesn't look to be too much of a change in track or QPF. This run's not gonna cut it for a major storm. I'm not sure the extremely light precip will even overcome the dry air to even make it to the surface.

Another GFS fail.

[MotoWeatherman]

12z GFS shows a nice ZR event for north GA.  The flow at 500mb remains form the WNW the whole time so that screams suppression for areas further west of GA unfortunately.  GFS QPF reflects that with around .10" or less over much of NC.  Based on this run I would expect a sleet to snow to ZR from ATL northeastward.  With such a light QPF in the carolinas and the low dewpoints my concern would be a nice virga storm for many areas outside the MTNs.  Of course this is just reading the 12z GFS verbatim IMHO.

[tnweathernut]

Per Robert:

 

Winter Storm Possible For : KY/WVa/VA/NC/ETN/nSC/neGA
The new GFS keeps surface temps below freezing in strong damming event down to Clemson, SC on Friday, with overrunning moisture, snow will spread across Kentucky, West Virginia, most of Virginia and northern NC on Friday, with mixed bag in Upstate SC and northeast GA and east TN. But GFS amounts are much lower than ECMWF model.
I'll have a full update at www.wxsouth.com after 12z ECMWF model run

[Cold Rain]

The track has definitely come in farther south, so that's a good trend. But man, that wave coming into the NW is not allowing it to dig much at all.

[FallsLake]

This run gives  N GA, upstate of SC and NC a very light glaze. Euro needs to really be watched. The GFS is VERY light on QPF. 

Even this scenario would be major in since of affects on roads. .1 liquid on the frozen pavement would be worse that 5 inches of snow falling on warm pavement.  

[Lookout]

@81 freezing drizzle in much of NC...north GA still freezing. Nice CAD sig. 

 

Indeed. This is a pretty cold wedge with regards to the boundary layer...20s in many parts of north ga when the precip starts to move in. and importantly it's deep..reaching up to 875mb to 900mb initially, which means the gfs is likely breaking the wedge way too fast. Per gfs though, even if it's true, the precip is mainly over with by the time it does break.

N GA could end up with the max of .25 of QPF....mountains around .20 and the usual zones between the mountains and eastern NC are around .10 per the GFS. 

Better than nothing but the "trend" is your friend" as they say. Love to see the other models come around to this. Since this would be a colder than average wedge, even 0.25 would make a mess on the roads.

[Brick Tamland]

Looks a little cooler than the two previous runs, but there doesn't look to be too much of a change in track or QPF. This run's not gonna cut it for a major storm. I'm not sure the extremely light precip will even overcome the dry air to even make it to the surface.

Another GFS fail.

 

But the trend is better. At least it is showing something and moved south.

[msuwx]

Consider me confused.  The models seems to be indicating a Low going up the apps or towards Ohio. How is CLT supposed to get frozen precipitation out of this? I understand the principal of CAD and how it's going to be relatively cold, but I don't see a mechanism to get both moisture AND cold in here at the same time when our Low is well to the west.  Experience tells me this system is a very cold rain, or dry.  At best maybe something token at the onset for I-40 north.  Or is the synoptic set up that the Low is going to trend south?  No comprendea

With this type of setup, you don't need a monster high anchored in over the Northeast for CAD. The initial cold and dry air will get locked in by precip, assuming there is some, as evaporation takes place. Since this isn't a huge storm system, you don't really get the massive warming, either at the surface on south winds, or from aloft due to high precip rates. 

 

This is definitely the type of system can at least be a nuisance type system for some areas...maybe more depending on precip amounts. But since the air is so dry,there is a definite ceiling for precip totals. 

[calculus1]

12Z GFS soundings for Hickory.  For what little precip there is, it still appears to start as snow at Hickory and transition to the ZR/IP.  This low track is such a traditionally bad track for this area, I'm not surprised that the GFS backed off on the precip totals here.  Usually, the mountains wring out most of the moisture, we get left looking at clear skies above and clouds to the west.

 

Date: 3 day AVN valid 12Z FRI 25 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   226                                                                 SFC  977   412  -5.8 -18.9  35 13.1  -8.7 154   5 269.2 269.3 265.8 271.7  0.88  2  950   627  -7.9 -20.0  37 12.1 -10.4 162   7 269.2 269.3 265.7 271.5  0.82  3  900  1045  -9.5 -21.0  39 11.5 -11.8 193  12 271.8 271.9 267.4 274.1  0.80  4  850  1491  -3.1  -9.6  60  6.6  -5.3 243  21 282.9 283.3 276.2 289.2  2.16  5  800  1975  -0.7  -3.4  82  2.7  -1.8 265  35 290.5 291.1 281.9 301.3  3.72  6  750  2489  -3.0  -4.3  91  1.2  -3.6 272  44 293.3 293.9 283.1 304.2  3.72  7  700  3032  -5.4  -7.9  83  2.5  -6.4 273  48 296.5 297.0 283.6 305.6  3.02  8  650  3613  -6.4 -15.8  47  9.3  -9.4 272  52 301.7 302.0 284.2 307.1  1.72  9  600  4236  -8.7 -28.0  19 19.3 -13.1 269  57 306.0 306.1 284.6 308.1  0.63 10  550  4906 -11.8 -34.7  13 22.9 -16.0 268  62 310.1 310.1 285.8 311.4  0.37 11  500  5629 -16.4 -27.5  38 11.1 -18.8 265  66 313.1 313.2 287.3 315.8  0.80 12  450  6415 -19.8 -21.5  86  1.7 -20.2 265  75 318.4 318.7 289.8 323.6  1.53 13  400  7285 -22.9 -23.1  98  0.2 -22.9 271  82 325.3 325.6 291.9 330.5  1.49 14  350  8252 -29.2 -29.3 100  0.0 -29.2 267  90 329.3 329.5 292.5 332.8  0.97 15  300  9333 -38.2 -38.3  99  0.1 -38.2 267  97 331.6 331.7 292.6 333.3  0.47 16  250 10559 -48.6 -48.6 100  0.0 -48.6 273 104 333.9 333.9 292.9 334.6  0.19 17  200 11984 -60.9 -61.1  98  0.2 -60.9 279 111 336.3 336.3 293.4 336.5  0.05 18  150 13731 -68.1 -69.3  85  1.2 -68.1 284 120 352.7 352.7 297.3 352.8  0.02 19  100 16170 -70.1 -79.8  23  9.6 -70.2 277  88 392.3 392.3 304.1 392.3  0.01TRP                                             0                              WND                                             0                              Sounding variables and indices1000-500 mb thick:      5403.03 mFreezing level:      Surface below freezingWetbulb zero:        Below groundPrecipitable water:        0.45 inches

 

 

Date: 3.5 day AVN valid 0Z SAT 26 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   138                                                                 SFC  966   410  -1.9  -3.7  88  1.7  -2.6 230   5 273.9 274.4 272.4 282.1  3.01  2  950   548  -1.7  -3.6  87  1.9  -2.4 241  11 275.5 276.0 273.4 283.9  3.07  3  900   981   2.1  -0.3  84  2.4   1.0 269  24 283.7 284.4 279.3 295.4  4.15  4  850  1442   0.4  -1.4  87  1.8  -0.4 274  39 286.6 287.3 280.6 298.2  4.06  5  800  1927  -1.2  -6.9  65  5.7  -3.4 276  47 289.9 290.4 280.6 298.2  2.85  6  750  2441  -1.8 -16.7  31 14.9  -6.4 275  57 294.6 294.8 280.8 298.9  1.38  7  700  2988  -2.8 -28.3  12 25.5  -8.8 271  67 299.4 299.5 281.8 301.2  0.53  8  650  3574  -3.8 -35.2   7 31.3 -10.2 270  74 304.6 304.7 283.7 305.7  0.30  9  600  4202  -6.5 -35.2   8 28.7 -12.3 272  78 308.5 308.6 285.2 309.7  0.32 10  550  4875 -11.1 -33.7  14 22.6 -15.4 274  83 310.9 311.0 286.2 312.4  0.40 11  500  5600 -15.3 -34.1  18 18.8 -18.7 274  88 314.4 314.4 287.4 315.9  0.43 12  450  6389 -20.1 -36.3  22 16.1 -22.7 274  93 317.9 318.0 288.5 319.3  0.38 13  400  7251 -26.3 -41.5  23 15.2 -28.1 274  97 320.8 320.9 289.3 321.8  0.25 14  350  8202 -33.1 -48.2  21 15.1 -34.3 272  97 324.2 324.2 290.2 324.7  0.14 15  300  9266 -41.8 -52.3  31 10.5 -42.3 273  99 326.5 326.5 290.8 326.9  0.10 16  250 10475 -51.3 -56.1  56  4.8 -51.5 276 104 329.8 329.8 291.7 330.1  0.08 17  200 11895 -59.0 -61.9  69  2.9 -59.0 279 106 339.4 339.4 294.2 339.6  0.05 18  150 13689 -61.3 -69.3  34  8.0 -61.4 277 102 364.5 364.5 299.6 364.6  0.02 19  100 16167 -67.9 -80.1  16 12.2 -68.0 277  87 396.5 396.5 304.8 396.5  0.01TRP                                             0                              WND                                             0                              Sounding variables and indices1000-500 mb thick:      5462.52 mFreezing level:      Surface below freezingFreezing level:          927.73 mb =   740.88 m =  2430.67 ftFreezing level:          836.36 mb =  1574.50 m =  5165.63 ftWetbulb zero:        Below groundPrecipitable water:        0.36 inches

[packbacker]

Look at the amped Euro from last night to todays 12z GFS, they are literally trending apart from each other, I would have really though one would have caved today and unfortunately the Euro is the only one left.

 

0z Euro...

 

 

 

12z GFS (very flat)

 

[packbacker]

12z Ukie, low running right through TN, not sure if it would dig south a little more like the Euro or start heading NE.

 

[SnowNiner]

With this type of setup, you don't need a monster high anchored in over the Northeast for CAD. The initial cold and dry air will get locked in by precip, assuming there is some, as evaporation takes place. Since this isn't a huge storm system, you don't really get the massive warming, either at the surface on south winds, or from aloft due to high precip rates. 

 

This is definitely the type of system can at least be a nuisance type system for some areas...maybe more depending on precip amounts. But since the air is so dry,there is a definite ceiling for precip totals. 

 

Thanks for the reply Matt.  Definitely sounds like a fine line and very complex.  Agreed on the dry air too, I noticed how cold it was this morning, but no frost.  Hopefully this will be a Johnny Cash system for CLT....and we can walk the line! 

[packbacker]

You would have to think the UK with this look would be more Euro'ish, but we will find out in about 20 mins...

 

[Lookout]

12z GFS shows a nice ZR event for north GA.  The flow at 500mb remains form the WNW the whole time so that screams suppression for areas further west of GA unfortunately.  GFS QPF reflects that with around .10" or less over much of NC.  Based on this run I would expect a sleet to snow to ZR from ATL northeastward.  With such a light QPF in the carolinas and the low dewpoints my concern would be a nice virga storm for many areas outside the MTNs.  Of course this is just reading the 12z GFS verbatim IMHO.

Based purely on the 12z soundings, I think it might start off as a little sleet to start with but is mainly freezing rain as the mid levels warm very quickly (800 to 850mb at 3c) so I  Don't see much chance of snow unless it comes it earlier...however we've seen the models be too slow with the leading precip before. But just based on this run and the soundings, it's 98% freezing rain, and the rest is a little sleet at the start due to the very dry air. We'll see though.

[BullCityWx]

Some of the highest impact ZR storms are the ones with lighter precip and lower temps like the GFS has.

[bhamwx205]

You would have to think the UK with this look would be more Euro'ish, but we will find out in about 20 mins...

what is keeping that from digging further down to the gulf

[calculus1]

Some of the highest impact ZR storms are the ones with lighter precip and lower temps like the GFS has.

 

I just took a glance at the 2m temps on the latest run of the GFS.  12Z does not have Hickory getting above freezing at any point on Friday.  So, whatever falls, should stick.

[MotoWeatherman]

Based purely on the 12z soundings, I think it might start off as a little sleet to start with but is mainly freezing rain as the mid levels warm very quickly (800 to 850mb at 3c) so I  Don't see much chance of snow unless it comes it earlier...however we've seen the models be too slow with the leading precip before. But just based on this run and the soundings, it's 98% freezing rain, and the rest is a little sleet at the start due to the very dry air. We'll see though.

I should have framed my comment a little better regarding the snow.  IMBY in far NE GA the column should wetbulb briefly below freezing which could allow for a brief period of snow.  I've seen it happen before but it's more of just a novelty before the sleet/ZR takes back over quickly.

 

Date: 66 hour AVN valid 6Z FRI 25 JAN 13Station: 34.59,-83.93Latitude:   34.59Longitude: -83.93-------------------------------------------------------------------------------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   236                                                                 SFC  970   479  -4.4  -9.3  69  4.9  -5.9 103   7 271.1 271.4 269.0 276.5  1.94  2  950   640  -5.1 -11.4  61  6.3  -6.9 105  12 272.0 272.3 269.1 276.7  1.67  3  900  1064  -5.4 -12.4  58  7.0  -7.4 133  14 275.9 276.2 271.5 280.6  1.63  4  850  1515  -1.5  -8.6  58  7.1  -4.0 225  16 284.6 285.0 277.3 291.4  2.34  5  800  2000  -0.1  -4.8  70  4.7  -2.0 267  29 291.1 291.6 281.7 300.8  3.34  6  750  2516  -0.4 -10.6  46 10.1  -4.1 273  32 296.1 296.5 282.6 303.0  2.28  7  700  3068  -0.1 -22.2  17 22.1  -6.5 273  34 302.3 302.5 283.5 305.3  0.92  8  650  3659  -2.5 -32.4   8 29.9  -9.2 270  38 306.2 306.2 284.4 307.5  0.39  9  600  4289  -5.9 -38.3   6 32.4 -12.1 271  42 309.2 309.3 285.4 310.1  0.23 10  550  4965  -9.3 -43.5   4 34.1 -14.8 272  47 313.0 313.0 286.6 313.6  0.15 11  500  5696 -13.2 -47.2   4 34.0 -17.9 274  52 316.9 317.0 287.9 317.4  0.11 12  450  6491 -17.3 -45.7   7 28.3 -21.1 278  58 321.4 321.5 289.3 322.0  0.14

[Bevo]

The track has definitely come in farther south, so that's a good trend. But man, that wave coming into the NW is not allowing it to dig much at all.

 

 

what is keeping that from digging further down to the gulf

 

I believe CR is is right with his idea of that NW energy.

[RaleighWx]

I did write a little article this morning on Friday's potential for those interested.

 

http://www.examiner.com/article/a-cold-week-ahead-with-wintry-weather-possible-by-friday

[Brick Tamland]

Some of the highest impact ZR storms are the ones with lighter precip and lower temps like the GFS has.

 

Yes, that is what I am saying. It doesn't take much to cause problems, and with temps as low as they are going to be this week, it will start to stick fast on the roads. I have seen plenty of havoc around here with just minor freezing drizzle events. I think it happened more often in the 80s and 90s, though.

[tnweathernut]

what is keeping that from digging further down to the gulf

 

Lack of better ridging on the west coast. It can only dig so far without a really tall ridge.

[Lookout]

I should have framed my comment a little better regarding the snow.  IMBY in far NE GA the column should wetbulb briefly below freezing which could allow for a brief period of snow.  I've seen it happen before but it's more of just a novelty before the sleet/ZR takes back over quickly.

 

Date: 66 hour AVN valid 6Z FRI 25 JAN 13Station: 34.59,-83.93Latitude:   34.59Longitude: -83.93-------------------------------------------------------------------------------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   236                                                                 SFC  970   479  -4.4  -9.3  69  4.9  -5.9 103   7 271.1 271.4 269.0 276.5  1.94  2  950   640  -5.1 -11.4  61  6.3  -6.9 105  12 272.0 272.3 269.1 276.7  1.67  3  900  1064  -5.4 -12.4  58  7.0  -7.4 133  14 275.9 276.2 271.5 280.6  1.63  4  850  1515  -1.5  -8.6  58  7.1  -4.0 225  16 284.6 285.0 277.3 291.4  2.34  5  800  2000  -0.1  -4.8  70  4.7  -2.0 267  29 291.1 291.6 281.7 300.8  3.34  6  750  2516  -0.4 -10.6  46 10.1  -4.1 273  32 296.1 296.5 282.6 303.0  2.28  7  700  3068  -0.1 -22.2  17 22.1  -6.5 273  34 302.3 302.5 283.5 305.3  0.92  8  650  3659  -2.5 -32.4   8 29.9  -9.2 270  38 306.2 306.2 284.4 307.5  0.39  9  600  4289  -5.9 -38.3   6 32.4 -12.1 271  42 309.2 309.3 285.4 310.1  0.23 10  550  4965  -9.3 -43.5   4 34.1 -14.8 272  47 313.0 313.0 286.6 313.6  0.15 11  500  5696 -13.2 -47.2   4 34.0 -17.9 274  52 316.9 317.0 287.9 317.4  0.11 12  450  6491 -17.3 -45.7   7 28.3 -21.1 278  58 321.4 321.5 289.3 322.0  0.14

 

Yeah I've seen it too. As you said, If it happens it will be very brief since the mid levels warm so quickly. It's always amazed me how quickly the mid levels warm.

 

That said, notice how cold surface temps are before anything falls. As I said, with such cold temps before and during the event, everything should freeze to the roads...especially bridges.  Like jeremy said, some of the worst impacts happen in situations like this in terms of road conditions, even if you don't get much in terms of precip. 

[griteater]

I did write a little article this morning on Friday's potential for those interested.

 

http://www.examiner.com/article/a-cold-week-ahead-with-wintry-weather-possible-by-friday

 

Nice write-up Allan.  Indeed, MJO headed for Phase 8 in early Feb per phase charts.  Overnight superensemble mean for day 8-14 is chilly.

 

 

http://imageshack.us/photo/my-images/707/814.png/'>

[Brick Tamland]

That said, notice how cold surface temps are before anything falls. As I said, with such cold temps before and during the event, everything should freeze to the roads...especially bridges.  Like jeremy said, some of the worst impacts happen in situations like this in terms of road conditions, even if you don't get much in terms of precip. 

 

Yes, snow is pretty to look at, but it's these kind of events that usually cause the most problems around my area.

[packbacker]

GGEM shifted way south from its 0z run, not quite as far as Euro though

[franklin NCwx]

The CMC has come very far south now too. Looks like yesterdays 12z euro with surface low placement.

[tnweathernut]

Here is Allan's map showing wintry potential.  I would think it might be overdone for our area over much of east TN, but I would love to be wrong.  Our mountains could do well, but just not feeling it for the lower valleys (yet).

 

Just looking at the current models...............it would seem to provide for more rain/mix than snow. I am hoping for a better trend in the coming days.

Thank you for your thoughts and map Allan.  We appreciate all your hard work and contributions to our board.

[tnweathernut]

Modeling looking VERY good for the CAD areas of NC at this point.  Definite trends are in your favor guys!

[eyewall]

The GFS just appears to be a mess to me. I don't think it quite knows how to handle this. Also the parent high is weak and wouldn't sustain much of a wedge (in-situ more than anything else as opposed to truly classical or hybrid). The 1030's high in the Northern Plains is not in a good CAD spot obviously as well. The Euro has a stronger 1030's parent high to start but it doesn't sustain itself as it drifts east and our storm develops (I don't have full access unfortunately so can't see the inbetween time stamps). It is showing a better defined Miller B transitioning to a single and much more robust coastal low as compared to the GFS. So where does this leave us? At low confidence waiting for this afternoon's Euro and future GFS runs to see if it can get a better handle.

 

PS: If you want a real solid CAD event you want to see a parent high of at least 1035 mb and ideally 1040's or better. It would of course ideally be over Ontario/western NY or so.