Nov. 27th - Nov. 29th Upper Level Low

[Lookout]

Yep...and the 0z GFS is showing stronger signs for Tuesday on the latest run.

You can clearly see the strong vort lobe moving south on the backside of the ULL along the MS/AL border and watch it drag the 540 contour south with it as the vort lobe rounds the base of the ULL.

And combine all that with 90%+RH thru 500mb and sub freezing layer down to below 925mb (almost to 950mb), and the snow opportunity looks pretty good right now. I'm not expecting much if any accumulation IMBY but above 2,000ft could coat the grassy areas in GA.

Although I haven't had a chance to post much, I've been following this since it first started to show up as well. As I said previously, and as we all know by now, surface to 950mb temps and dewpoints/wetbulbs are not that supportive of snow at the surface on the face of it. It will be interesting to see what wins out here..the snow or the temps.

What I think will be a good indicator is what happens to the west today, as snow is mixing in some spots now. Currently 950mb temps are subfreezing with 975mb to surface temps well above freezing. A bit colder at 950mb than what the models are showing for us so but then again precip rates are not impressive either and likely aren't as intense as what will be moving through tomorrow morning...so it's not an exactly fitting yet. However, as the day and evening progresses and we see where the snow is falling vs boundary layer conditions (along with precip rates), we should get a good idea imo by this evening on whether or not we will see snow reach the surface here.

My position hasn't changed much over the last 24 to 36 hours, I do think we will see at least a mix and even a changeover to all snow in areas that are lucky enough to get under some intense rates for a little while in general. Even though 950mb to surface temps aren't that cold, with such cold mid level temps and freezing levels being as low as they are, it will help a lot in getting the flakes to survive the trip. If our 850mb temps were only -1c or 2c, I would be saying all rain for most but -4c to -6c is probably cold enough to allow some snow to reach the surface in areas with half decent precip rates.

The question though is really where is it most likely to happen. (not counting elevations above 1000 to 1500 feet north of rome to gainesville to toccoa where snow is an almost certainty if any precip falls).

As has been the case for the last 24 to 36 hours, the nam/gfs actually have the coldest 950mb to 975mb temps along or SOUTH of atlanta to athens. Now mind you, in some cases it's only 0.5c to at most 1c, but that is actually pretty huge in such a situation like this. So I would not at all be surprised to see areas further south with more snow than areas further north (again not counting higher elevations in the mountains). The further east you go the harder it will be though for sure as surface temps rise and the models show in particular 975mb temps rising. Not sure if I will see anything here because of that later start time and warming but I'll likely have to be heading to gainesville early tomorrow anyway.

At any rate, One thing that will likely have an impact on this is exactly where the snow and the resulting max cooling in the lowest layers out west happens. Following the 950mb to surface flow, If it happens a little further east, areas further north will be a little cooler and if it happens further west, areas further south will see more cooling.

This is one of those situations though that are almost going to be a minute by minute thing to watch but I think watching exactly where the heaviest precip and resulting max boundary layer cooling occurs and what the conditions were before the snow takes place over tn, ms/al will at least give us more of an idea of what to expect.

[CoastalWx]

If I had to guess, I think the areas sw-s-se of Memphis have the best shot of getting into the best banding, although it's possible MEM may be far enough sw to avoid the DS. Maybe Holly Springs to Senaobia to Oxford Triangle? Tunica could get it good too.

[CoastalWx]

If I had to guess, I think the areas sw-s-se of Memphis have the best shot of getting into the best banding, although it's possible MEM may be far enough sw to avoid the DS. Maybe Holly Springs to Senaobia to Oxford Triangle? Tunica could get it good too.

Euro actually likes MEM and just se.

[Tyler Penland]

FWIW HRRR likes West Tennessee/ North Mississippi

[tennvolfan]

Latest RUC (or one that I have access to) already looks a day late and a dollar short on initializing precip, ESP given that its already 60 miles west of Memphis and it shouldnt even be that far west until several hours later.

[MotoWeatherman]

Although I haven't had a chance to post much, I've been following this since it first started to show up as well. As I said previously, and as we all know by now, surface to 950mb temps and dewpoints/wetbulbs are not that supportive of snow at the surface on the face of it. It will be interesting to see what wins out here..the snow or the temps.

What I think will be a good indicator is what happens to the west today, as snow is mixing in some spots now. Currently 950mb temps are subfreezing with 975mb to surface temps well above freezing. A bit colder at 950mb than what the models are showing for us so but then again precip rates are not impressive either and likely aren't as intense as what will be moving through tomorrow morning...so it's not an exactly fitting yet. However, as the day and evening progresses and we see where the snow is falling vs boundary layer conditions (along with precip rates), we should get a good idea imo by this evening on whether or not we will see snow reach the surface here.

My position hasn't changed much over the last 24 to 36 hours, I do think we will see at least a mix and even a changeover to all snow in areas that are lucky enough to get under some intense rates for a little while in general. Even though 950mb to surface temps aren't that cold, with such cold mid level temps and freezing levels being as low as they are, it will help a lot in getting the flakes to survive the trip. If our 850mb temps were only -1c or 2c, I would be saying all rain for most but -4c to -6c is probably cold enough to allow some snow to reach the surface in areas with half decent precip rates.

The question though is really where is it most likely to happen. (not counting elevations above 1000 to 1500 feet north of rome to gainesville to toccoa where snow is an almost certainty if any precip falls).

As has been the case for the last 24 to 36 hours, the nam/gfs actually have the coldest 950mb to 975mb temps along or SOUTH of atlanta to athens. Now mind you, in some cases it's only 0.5c to at most 1c, but that is actually pretty huge in such a situation like this. So I would not at all be surprised to see areas further south with more snow than areas further north (again not counting higher elevations in the mountains). The further east you go the harder it will be though for sure as surface temps rise and the models show in particular 975mb temps rising. Not sure if I will see anything here because of that later start time and warming but I'll likely have to be heading to gainesville early tomorrow anyway.

At any rate, One thing that will likely have an impact on this is exactly where the snow and the resulting max cooling in the lowest layers out west happens. Following the 950mb to surface flow, If it happens a little further east, areas further north will be a little cooler and if it happens further west, areas further south will see more cooling.

This is one of those situations though that are almost going to be a minute by minute thing to watch but I think watching exactly where the heaviest precip and resulting max boundary layer cooling occurs and what the conditions were before the snow takes place over tn, ms/al will at least give us more of an idea of what to expect.

Knowing my luck that is exactly what will happen. Our last two ULL events have given MBY 1) RAIN while snow south and 2) Snow while above freezing the whole time while south of me got more.

[DaculaWeather]

Down to 546

[DaculaWeather]

Very odd line here... Winds change speed dramatically behind it.

[Isopycnic]

Very odd line here... Winds change speed dramatically behind it.

It's almost like a front of some kind.

[Tyler Penland]

Very odd line here... Winds change speed dramatically behind it.

That's pretty interesting. Looks like it'll get to you before it gets to me. Reckon we'll have to run outside and see haha.

It runs all the way down the line towards Macon. Actually, it runs all the way to Florida. And well down into Florida at that.

[DaculaWeather]

4 contour 546 now

[LithiaWx]

4 contour 546 now

Looks like it has gone negative tilt also, if I'm using the term correctly. Also noticing the -26 temps at 500mb.

[MotoWeatherman]

Latest GFS and NAM still look pretty decent for snow development across north GA and into Western NC tomorrow.

Column is saturated through 700mb with 700mb temps of -12 and 850's of -5 from ATL northward. The boundary layer will still be an issue as the freezing level is above 950mb so this is going to depend heavily on precip rates for how much snow actually makes it to the surface. Lookout went into great detail about this earlier. I don't think we will have any issues with snow flake production in the upper levels though.

[Shawn]

Latest GFS and NAM still look pretty decent for snow development across north GA and into Western NC tomorrow.

Column is saturated through 700mb with 700mb temps of -12 and 850's of -5 from ATL northward. The boundary layer will still be an issue as the freezing level is above 950mb so this is going to depend heavily on precip rates for how much snow actually makes it to the surface. Lookout went into great detail about this earlier. I don't think we will have any issues with snow flake production in the upper levels though.

Edit:

[DaculaWeather]

It looks like the 850's are retrograding westward, more in line with the ULL.

[Lookout]

Latest GFS and NAM still look pretty decent for snow development across north GA and into Western NC tomorrow.

Column is saturated through 700mb with 700mb temps of -12 and 850's of -5 from ATL northward. The boundary layer will still be an issue as the freezing level is above 950mb so this is going to depend heavily on precip rates for how much snow actually makes it to the surface. Lookout went into great detail about this earlier. I don't think we will have any issues with snow flake production in the upper levels though.

Some encouraging news on the 12z gfs/nam this morning for north ga. Both models are a bit colder at the surface to 950mb. In fact, it appears to be an all snow or mostly snow sounding.

Here is the 24 hour gfs for gainesville sounding. Both models now have temps in the mid 30s instead of upper 30s at the surface and have cooled 950mb temps from around 1.5c to very close to freezing, around 0.5c. IF that verifies, it looks like there will be a period of mostly snow for a lot of north Ga as that precip with the vort moves through, dependent of course on how well organized/heavy the precip is. At the least, this mornings runs have increased the chances that flakes will fly for most in north ga.

Unfortunately for central Ga, both models are a bit drier than previous runs with the nam showing most of the precip falling over north Ga. However, Temps appear cold enough still but moisture is the issue this run for central ga.

Just one run though so we will see if the trend holds.

Note saturation even up to 500mb.

Date: 24 hour AVN valid 12Z TUE 29 NOV 11
Station: KGVL
Latitude:   34.27
Longitude: -83.83
-------------------------------------------------------------------------------
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    92                                                                 
SFC  966   375   1.4   0.7  95  0.7   1.1 197   8 277.3 278.0 276.0 288.7  4.15
 2  950   506   0.6  -0.3  94  0.9   0.2 209  12 277.8 278.4 275.9 288.5  3.92
 3  900   938  -2.7  -3.2  96  0.5  -2.9 220  16 278.8 279.3 275.7 288.1  3.35
 4  850  1389  -4.8  -6.0  92  1.2  -5.2 227  21 281.1 281.6 276.3 289.3  2.88
 5  800  1864  -7.0  -8.3  91  1.2  -7.5 226  25 283.7 284.1 277.2 291.0  2.56
 6  750  2366  -8.4 -10.7  83  2.3  -9.2 219  31 287.4 287.8 278.6 294.0  2.25
 7  700  2900 -10.0 -14.7  68  4.7 -11.3 211  35 291.4 291.7 279.9 296.7  1.75
 8  650  3468 -12.7 -16.4  74  3.7 -13.7 209  36 294.6 294.9 281.1 299.6  1.63
 9  600  4075 -15.9 -18.1  83  2.2 -16.5 214  39 297.7 297.9 282.4 302.4  1.53
10  550  4726 -20.0 -21.5  88  1.5 -20.3 220  44 300.4 300.6 283.1 304.3  1.24
11  500  5427 -23.9 -24.4  96  0.5 -24.0 228  51 303.9 304.1 284.3 307.3  1.06

[MotoWeatherman]

Some encouraging news on the 12z gfs/nam this morning for north ga. Both models are a bit colder at the surface to 950mb. In fact, it appears to be an all snow or mostly snow sounding.

Here is the 24 hour gfs for gainesville sounding. Both models now have temps in the mid 30s instead of upper 30s at the surface and have cooled 950mb temps from around 1.5c to very close to freezing, around 0.5c. IF that verifies, it looks like there will be a period of mostly snow for a lot of north Ga as that precip with the vort moves through, dependent of course on how well organized/heavy the precip is. At the least, this mornings runs have increased the chances that flakes will fly for most in north ga.

Unfortunately for central Ga, both models are a bit drier than previous runs with the nam showing most of the precip falling over north Ga. However, Temps appear cold enough still but moisture is the issue this run for central ga.

Just one run though so we will see if the trend holds.

Note saturation even up to 500mb.

Date: 24 hour AVN valid 12Z TUE 29 NOV 11
Station: KGVL
Latitude:   34.27
Longitude: -83.83
-------------------------------------------------------------------------------
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    92                                                                 
SFC  966   375   1.4   0.7  95  0.7   1.1 197   8 277.3 278.0 276.0 288.7  4.15
 2  950   506   0.6  -0.3  94  0.9   0.2 209  12 277.8 278.4 275.9 288.5  3.92
 3  900   938  -2.7  -3.2  96  0.5  -2.9 220  16 278.8 279.3 275.7 288.1  3.35
 4  850  1389  -4.8  -6.0  92  1.2  -5.2 227  21 281.1 281.6 276.3 289.3  2.88
 5  800  1864  -7.0  -8.3  91  1.2  -7.5 226  25 283.7 284.1 277.2 291.0  2.56
 6  750  2366  -8.4 -10.7  83  2.3  -9.2 219  31 287.4 287.8 278.6 294.0  2.25
 7  700  2900 -10.0 -14.7  68  4.7 -11.3 211  35 291.4 291.7 279.9 296.7  1.75
 8  650  3468 -12.7 -16.4  74  3.7 -13.7 209  36 294.6 294.9 281.1 299.6  1.63
 9  600  4075 -15.9 -18.1  83  2.2 -16.5 214  39 297.7 297.9 282.4 302.4  1.53
10  550  4726 -20.0 -21.5  88  1.5 -20.3 220  44 300.4 300.6 283.1 304.3  1.24
11  500  5427 -23.9 -24.4  96  0.5 -24.0 228  51 303.9 304.1 284.3 307.3  1.06

I hadn't even looked at soundings so thanks for posting that. From where I sit north of Gainesville and up another 500ft+ in elevation this could be a fun day tomorrow.

As far as today is concerned....YAWN.......good rain event but looks like a big bust for MBY from what the models were showing.

[dsaur]

I hadn't even looked at soundings so thanks for posting that. From where I sit north of Gainesville and up another 500ft+ in elevation this could be a fun day tomorrow.

As far as today is concerned....YAWN.......good rain event but looks like a big bust for MBY from what the models were showing.

Yeah, I don't much understand your situation. I get it down here...the lower end of the rain shield has been very ragged, with more holes than showers (and it has often been this way over the last few years, even with a good gulf tap) , but up there the shield looks to have been much more in tact...yet there you are barely more than me. T

[DaculaWeather]

546 4 contour

[MotoWeatherman]

Yeah, I don't much understand your situation. I get it down here...the lower end of the rain shield has been very ragged, with more holes than showers (and it has often been this way over the last few years, even with a good gulf tap) , but up there the shield looks to have been much more in tact...yet there you are barely more than me. T

It's all been VERY light for the most part. The heavy stuff has been to my east and my west and north of me. Guess it's just my bad luck on this one.

Below is a precip map since midnight ending at 1215pm.

[Northern Foothills Snowman]

This may have already been discussed and if so just ignore my question.Hasn't there been several upper level low that have miander in our area this fall ?The other ones were a little more north .I'm just wondering if this is a pattern we will continue to see this winter .Also I thought during a LaNina the moisture from the gulf of Mexico was closed off?

[Shawn]

This may have already been discussed and if so just ignore my question.Hasn't there been several upper level low that have miander in our area this fall ?The other ones were a little more north .I'm just wondering if this is a pattern we will continue to see this winter .Also I thought during a LaNina the moisture from the gulf of Mexico was closed off?

It's not exactly closed just because it's a La Nina year. There was a pretty potent cut off not too long ago to our North also.

Good reading about La Nina : http://www.elnino.noaa.gov/lanina.html

[Cheeznado]

It will be nice to see snow- even if it melts. The heaviest will be north of me of course, may have to take a road trip tomorrow AM up 75. That would ease the sting of the rain disappointment here, will not even get an inch.

[ams30721us]

It will be nice to see snow- even if it melts. The heaviest will be north of me of course, may have to take a road trip tomorrow AM up 75. That would ease the sting of the rain disappointment here, will not even get an inch.

Geez! What in the world are yall doing with the rain over that way?? We had about 2.60' yesterday and over 1.35" today so far in the Dalton area and its still raining! I will be glad to share a little!

[scoresman]

Getting twitter and FB posts about rain/snow mix in Memphis with banding staring to show up on radar... Im in east Memphis and can only report cold rain

[FoothillsNC]

It will be nice to see snow- even if it melts. The heaviest will be north of me of course, may have to take a road trip tomorrow AM up 75. That would ease the sting of the rain disappointment here, will not even get an inch.

Yep the Metro region got sandwiched it looks like.

[MotoWeatherman]

FFC looks to be on board with the snow IMBY tomorrow. I agree...

This Afternoon: Occasional rain. The rain could be heavy at times. High near 60. South wind around 10 mph, with gusts as high as 15 mph. Chance of precipitation is 100%. New rainfall amounts between a half and three quarters of an inch possible.

Tonight: Rain likely before 4am, then rain and snow likely. Cloudy, with a low around 38. Calm wind becoming south around 5 mph. Chance of precipitation is 60%. Little or no snow accumulation expected.

Tuesday: Light snow likely, mainly before 1pm. Cloudy, with a high near 42. Southeast wind around 5 mph becoming southwest. Chance of precipitation is 70%. Little or no snow accumulation expected.

[NEGa]

It's all been VERY light for the most part. The heavy stuff has been to my east and my west and north of me. Guess it's just my bad luck on this one.

Below is a precip map since midnight ending at 1215pm.

thats sort of surprising - its been pouring on and off here all morning and i had over an inch when i left for work. the winds are pretty strong too - raining sideways at times.

i have court in the morning so i am fairly sure that will make sure it snows lol since i probably wont be able to see it

[Cheeznado]

Geez! What in the world are yall doing with the rain over that way?? We had about 2.60' yesterday and over 1.35" today so far in the Dalton area and its still raining! I will be glad to share a little!

Its been that way here almost all year- the ATL area screw hole is alive and well, especially at my house. I have not had over 4" in a month since June. If I get less than 3" through Dec. I will have had less than 40" for the year.

[toxictwister00]

Its been that way here almost all year- the ATL area screw hole is alive and well, especially at my house. I have not had over 4" in a month since June. If I get less than 3" through Dec. I will have had less than 40" for the year.

I haven't been keeping track throughout the whole summer, but I have noticed this happening a lot since Tropical Storm Lee. The city is always right on the edge of the heaviest rainfall.

Also temps continue to drop, now down to 50 at Hartsfield, those 40s will be streaming in here soon.