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

[Suncat]

What are we looking at for a rain potential for central NC, particularly around Raleigh. The reason I ask is because we are working on a study of a creek in Raleigh and need to capture some good rain events for storm runoff sampling and flow measurements.

Thanks in advance!

[NavarreDon]

6z GFS would be a complete disaster for the upslope regions of ne GA, nw SC and sw NC. It's setup is showing a once in 25 or 50 year event. I'm not taking it's qpf literally, as always it underdoes amounts in an upslope flow, but this event looks about as robust as any I've followed on these boards. The system doesn't pull down quite as much cold air since it doesn't fully phase a lot of the northern stream, but its still 5 full contours and would be cold enough core to have some snow eventually under it, probably Ark, Tn, Al, GA and eventually the mtns of NC. I'm not interested in that part of the storm yet, but the way the system cuts off so far west and has a super feed of Gulf moisture, then Atlantic moisture both poised to pivot right into Ga and the Carolinas, after some flash flooding all along the Gulf states. How quickly the dryslot moves in is a question mark, but usually the dry slot does sweep east, but in this case the system is so slow and stalls for nearly 48 hours, it still would easily transport a dangerous flood to the Apps. Extreme uplsope lift, with .50" an hour rates for quite a few hours would be experienced in the best lift of the southeast facing slopes. Better hope the system doesn't work out like this, that would be just too much water, and come on already saturated grounds. BTW, it still uses this storm as the pattern changer. Pretty tall PNA western ridge, colder trough in the central and east for a little while (but that probably won't last too long )

Here's a 54 hour loop:

Robert or any one, a couple Qs as I try to enhance the little weather knowledge I have. For a colder system are we looking for this to phase with northern energy? How does this compare to the X-mas storm of last year and how is it different as far as phasing & general setup? If it produces strong storms in the deep south will they rob moisture further north? Sorry for the idiot Qs & one of the mods can delete if needed. Thanks, Don

[msuwx]

By the way, for those keeping score at home, in relation to average through yesterday's numbers, RDU and ATL are about 1 degree or so above average, GSO, CLT, Athens, and GSP are almost exactly at average.This is for the month of November.

[FoothillsNC]

I love me some upper lows.

Great posts by many in this thread. Wherever this thing cuts off (if it happens as advertised by some models), sure looks like some snow is in the works for some. Ironic considering the recent warmth and the time of year. I don't recall too many such strong cutoff upper level lows this time of year producing snow as far south as this has the potential to. Of course I'm not nearly as educated in analogs and weather history as some are so is there any similar events like this we know of?

The May 1992 cutoff wasnt' as strong as this one is progged to be, and was actually warmer aloft. It was 3 contours best I can tell and was a good bit warmer than this is progged ...yet mega snow hit the higher Apps like Roan Mtn and Mt. Pisgah. Some wet flakes even made it to the ground directly under the core of ULL as it headed due north from central GA across GSP and Hendersonville, but since it was so warm aloft (about .5 or 0 at 850) it was mainly 5000 ft snowstorm. This storm cuts off earlier, is colder and doesn't make it that far east at first, so if it occurs as shown on GFS then I'd say snow is a good bet on the nw side right now looks like best chance would still be around TN, Ark. Mo. Bootheel and northern Al and nw GA at first, but the strange thing on this one is how it actually grows colder at the core, I think it goes to 536 heights at one point on GFS and has -4 to -6 air. Also, not all cutoff's can pull really good moisture into it's center, we've had a lot of ULL's lately that didn't do that so well, so each is different depending on where exactly and how its oriented. The May 1992 was a Georgia coastal and retrograded, so it was slam full of moisture from the Atlantic. Its still too far out to pinpoint but obviously we both like ULL's....cause they are super fun to watch. Here's some stuff from my files on the May 1992 storm. This was the storm that dropped 60" on mt Pisgah just sw of AVL and I drove to see it after heading to Roan earlier in the week, It was ending as I got there and melting fast, and was only waist deep when I pulled off the Parkway. I wish I had taken pics back then

[DaculaWeather]

Great loop here right now showing the piece of energy from the coast of California at least partially phasing with the energy dropping down the east side of the Rockies. The low bombs out, goes negative, and two waves of energy pass our area, the second bringing the chance of some snow to the north Georgia mountains.

http://mag.ncep.noaa.gov/NCOMAGWEB/appcontroller?prevPage=Model&MainPage=indexℑ=&page=Param&cycle=11%2F23%2F2011+06UTC&rname=UPPER+AIR+PARMS&pname=500_vort_ht&pdesc=&model=GFS&area=NAMER&cat=MODEL+GUIDANCE&fcast=Loop+All&areaDesc=North+America+-+US+Canada+and+northern+Mexico&prevArea=NAMER&currKey=model&returnToModel=&imageSize=M

[Brick Tamland]

Some snow in the mountains would be fun for those folks, but looks like we're going to really have to look out for severe weather around here on Monday.

[FoothillsNC]

The strong Alaskan vortex is probably the driver of this anomalous cutoff coming (if it indeed happens). The height anomalies in Ak. are still very low, almost off the spectrum so with a strong s/w rounding it, it helps to develop a quick ridge in Western Canada, which ultimately causes the deep cutoff in the South or Southeast.

[FoothillsNC]

Robert or any one, a couple Qs as I try to enhance the little weather knowledge I have. For a colder system are we looking for this to phase with northern energy? How does this compare to the X-mas storm of last year and how is it different as far as phasing & general setup? If it produces strong storms in the deep south will they rob moisture further north? Sorry for the idiot Qs & one of the mods can delete if needed. Thanks, Don

Looks like robbing won't occur b/c of the north-south oriented bands from say the Gulf to Tenn. then the band pivots se to nw fashion, and thats where you may end up getting pretty wet. The GFS is stalling it for about 48 hours, so the band would probably keep funneling a long time into western NC with copious heavy rain, slowly lifting north along the South Atlantic to Central Apps. By then, wrap around would be filling in over TN, Al, Ky and north GA (depending where the 850 and 5h low is) and that could be snow if its cold enough. GFS looks a little too cold, but there's time to iron that out after we know for sure where the cutoff is.

[Carvers Gap]

I take a day-off from the board and look what happens! Now, we have a possible cut-off low w/ heavy rain and snow possible somewhere in the region. It's pretty crazy how full the streams are right now. Again, I always remember JB talking about cold heading for where it has rained the most during fall. Well, this has been as sloppy a fall as I can remember. What that translates to for winter weather, I don't know. I'm still pretty nervoust about the potential for a warm winter. A possible good sign for next week's storm is tha the NAO ensembles are taking a bit of a dip/dive in the near future along w/ the AO. The NAO takes a look at negative territory while the AO goes neutral. I remember some conversation around the Halloween storm about the AO taking a dip that might have signalled the potential for that storm. I wonder if those might not be a signal for the potential upcoming storm.

[nrgjeff]

Agree flooding will be the news maker.

6z GFS would be a complete disaster for the upslope regions of ne GA, nw SC and sw NC. It's setup is showing a once in 25 or 50 year event. I'm not taking it's qpf literally, as always it underdoes amounts in an upslope flow, but this event looks about as robust as any I've followed on these boards. The system doesn't pull down quite as much cold air since it doesn't fully phase a lot of the northern stream, but its still 5 full contours and would be cold enough core to have some snow eventually under it, probably Ark, Tn, Al, GA and eventually the mtns of NC. I'm not interested in that part of the storm yet, but the way the system cuts off so far west and has a super feed of Gulf moisture, then Atlantic moisture both poised to pivot right into Ga and the Carolinas, after some flash flooding all along the Gulf states. How quickly the dryslot moves in is a question mark, but usually the dry slot does sweep east, but in this case the system is so slow and stalls for nearly 48 hours, it still would easily transport a dangerous flood to the Apps. Extreme uplsope lift, with .50" an hour rates for quite a few hours would be experienced in the best lift of the southeast facing slopes. Better hope the system doesn't work out like this, that would be just too much water, and come on already saturated grounds. BTW, it still uses this storm as the pattern changer. Pretty tall PNA western ridge, colder trough in the central and east for a little while (but that probably won't last too long )

Here's a 54 hour loop:

Even though it will snow at higher elevations, and likely change over mid-mountains, the damage will be done from heavy rain. Great post Foothills!

[LithiaWx]

This discussion going on in this thread is awesome! Loads of great information! Thanks folks!

FFC starting to bite...

LONG TERM /FRIDAY THROUGH TUESDAY/...

MODELS IN GOOD AGREEMENT UNTIL SUNDAY...DRY WITH THE UPPER RIDGE

MOVING OFF THE ATLANTIC COAST. LONGWAVE TROUGH DEVELOPING THROUGH

THE MISSISSIPPI VALLEY ON SUNDAY WITH RETURN MOISTURE MOVING INTO

THE CWA LOOKS REASONABLE FOR SHOWERS. AFTER THAT...BOTH MODELS

DEVELOP AN UPPER CLOSED LOW OVER THE SOUTHEAST...BUT LOCATION AND

TRACK ARE NOT CONSISTENT BETWEEN GFS AND ECMWF. HOWEVER...LOOKS

LIKE LOWS SHOULD BE IN THE 30S MONDAY THROUGH TUESDAY. HAVE GONE

AHEAD AND MENTIONED A CHANCE OF RAIN OR SNOW ACROSS THE EXTREME

NORTHERN COUNTIES FOR MONDAY NIGHT. WITH UNCERTAINTY IN THE

MODELS...THIS MAY CHANGE WITH UPCOMING NEW MODEL GUIDANCE.

[CandymanColumbusGA]

This system is going to have a bit of everything! I'm still concerned about a severe weather threat away from the actual low. Heavy rains, as Robert mentioned, could be devastating for some... Some of the models are already giving western South Carolina up to 2.5 inches of rain! I'm not as well versed with upslope events as others on the board here, but if I'm learning correctly, this will be SEVERELY underdone. If this solution were correct, which isn't a given, then I wouldn't be surprised to see some of NE GA/Western Carolinas/Eastern TN get 6+ inches of rain... The potential is certainly there, that's for sure!

The northern fringe AND who ever is DIRECTLY under this ULL could very well see flurries/snow... In fact! Take a look at what the Bufkit Warehouse is painting for Columbus, GA for Monday (THIS IS NOT LIKELY TO HAPPEN BUT STILL FUNNY TO LOOK AT!)

It also has BNA getting over 2 inches of snow...

It'll be interesting to see IF/WHERE the ULL sets up. It should be fun tracking from the Florida beaches... hahaa!

[downeastnc]

This possible event made me think of the Nov 21 2006 event in Southern SC were some saw several inches of snow in a rather small area. However there was a much larger area that saw a dusting in a area that lucky to see snow at all in any given winter much less several days before Thanksgiving. Ironically here several hundred miles to the north we had temps in the low 50's with light rain that day.

http://www.erh.noaa.gov/chs//text/PNSCHS_11222006.txt

[BullCityWx]

Just in case anyone is wondering, the 0z Euro is much too warm at the surface for anyone below 3K feet to see any snow through about 18z on Tuesday. I'd leave the GFS alone in the corner if I was y'all.

[UpstateSnow]

1322056674[/url]' post='1138722']

The May 1992 cutoff wasnt' as strong as this one is progged to be, and was actually warmer aloft. It was 3 contours best I can tell and was a good bit warmer than this is progged ...yet mega snow hit the higher Apps like Roan Mtn and Mt. Pisgah. Some wet flakes even made it to the ground directly under the core of ULL as it headed due north from central GA across GSP and Hendersonville, but since it was so warm aloft (about .5 or 0 at 850) it was mainly 5000 ft snowstorm. This storm cuts off earlier, is colder and doesn't make it that far east at first, so if it occurs as shown on GFS then I'd say snow is a good bet on the nw side right now looks like best chance would still be around TN, Ark. Mo. Bootheel and northern Al and nw GA at first, but the strange thing on this one is how it actually grows colder at the core, I think it goes to 536 heights at one point on GFS and has -4 to -6 air. Also, not all cutoff's can pull really good moisture into it's center, we've had a lot of ULL's lately that didn't do that so well, so each is different depending on where exactly and how its oriented. The May 1992 was a Georgia coastal and retrograded, so it was slam full of moisture from the Atlantic. Its still too far out to pinpoint but obviously we both like ULL's....cause they are super fun to watch. Here's some stuff from my files on the May 1992 storm. This was the storm that dropped 60" on mt Pisgah just sw of AVL and I drove to see it after heading to Roan earlier in the week, It was ending as I got there and melting fast, and was only waist deep when I pulled off the Parkway. I wish I had taken pics back then

I remember my parents took me up to Mount Pigah during that May 1992 storm. I was in the eight grade at the time, so the snow was up past my waist. I have been telling people about that storm for years and most think I am making it up. You don't see 5 feet of snow in January very often, much less May.

[FoothillsNC]

I remember my parents took me up to Mount Pigah during that May 1992 storm. I was in the eight grade at the time, so the snow was up past my waist. I have been telling people about that storm for years and most think I am making it up. You don't see 5 feet of snow in January very often, much less May.

Oh it was definitely deep. I'm very tall and it was to my upper thigh. The roads were just wet though at the time of it ending when I arrived. It was melting constantly from underneath. Sun was breaking through the clouds and silver sized dollar flakes were still falling. I'm sure somebody has pics if you googled it. People staying at Pisgah Inn that week were stranded.

[LithiaWx]

Just in case anyone is wondering, the 0z Euro is much too warm at the surface for anyone below 3K feet to see any snow through about 18z on Tuesday. I'd leave the GFS alone in the corner if I was y'all.

We just had two mets say that it would bring snow to areas like Atlanta at 1000' I'm not sure why there is such a difference of opinion here. Were you referring to a particular area?

[BullCityWx]

We just had two mets say that it would bring snow to areas like Atlanta at 1000' I'm not sure why there is such a difference of opinion here. Were you referring to a particular area?

Surface temps are at 5-6C across the entire south. That includes BNA, ATL, CLT, TYS, AVL, etc.

Here's the conditions at 18z Tuesday off the European, completely verbatim:

BNA: +6.3C 2mT, +4C 850

ATL: +6.2C 2mT, -2C 850

CLT: +8.6C 2mT, -1.6C 850

TYS: +4.8C 2mT, -0.6C 850

AVL: +6.5C 2mT, -1.4C 850

[LithiaWx]

I think the 12Z GFS is going to be disappointing for snow lovers.

so far through 126 only some light snow showers/flurries just west of the apps on the GFS.

[jdpilot]

Oh it was definitely deep. I'm very tall and it was to my upper thigh. The roads were just wet though at the time of it ending when I arrived. It was melting constantly from underneath. Sun was breaking through the clouds and silver sized dollar flakes were still falling. I'm sure somebody has pics if you googled it. People staying at Pisgah Inn that week were stranded.

I also drove up to Mt. Pisgah after the May 1992 storm. I too wish I would have taken pictures so that people would believe me when I tell them about the storm. I also remember seeing people in trucks, with Florida and Georgia plates, filling the beds with snow. If their beds had a tight seal, I'm sure they enjoyed their wading pools when they got home.

[FoothillsNC]

I think the 12Z GFS is going to be disappointing for snow lovers.

Yep, as has been the case and my thought was the earlier runs were too deep. The 12Z doesn't pull down nearly the northern energy, and it leaves some energy in the SW region but it does still sharpen up the trough along the Apps and begins to cutoff over the Apps by hour 120 or 126. The run still doesn't look quite right at that hour either, but its looking less likely of the deep Arkansas cutoff, since not that much energy gets shot due south. Still could be waffles I'm sure.

[CandymanColumbusGA]

Surface temps are at 5-6C across the entire south. That includes BNA, ATL, CLT, TYS, AVL, etc.

Yes, most places are between 3-6C across the south. That doesn't mean we can't see flurries/snow. It doesn't HAVE to be below freezing at the surface to see snow flakes, especially if the rest of the column is cold and saturated enough. There have been known instances where it snows as warm as 39/40 degrees... That's not to say it will accumulate, because it won't. But there very well could be flurries, at least according to the 0Z run of the Euro...

I'm not saying it will happen, just something fun to watch as we get closer!

[BullCityWx]

Yes, most places are between 3-6C across the south. That doesn't mean we can't see flurries/snow. It doesn't HAVE to be below freezing at the surface to see snow flakes, especially if the rest of the column is cold and saturated enough. There have been known instances where it snows as warm as 39/40 degrees... That's not to say it will accumulate, because it won't. But there very well could be flurries, at least according to the 0Z run of the Euro...

I'm not saying it will happen, just something fun to watch as we get closer!

I just cant see it snowing given those conditions and november climatology. If it's not cold enough to snow in Boone in November, it's not cold enough to snow anywhere in the lowlands.

[Thrasher Fan]

12z GFS = Buzzkill

[LithiaWx]

I just cant see it snowing given those conditions and november climatology. If it's not cold enough to snow in Boone in November, it's not cold enough to snow anywhere in the lowlands.

Yes, but there is a difference in what we think will happen and reading a model and saying if it supports snow or not.

[CandymanColumbusGA]

I just cant see it snowing given those conditions and november climatology. If it's not cold enough to snow in Boone in November, it's not cold enough to snow anywhere in the lowlands.

Fair enough good sir! There's a multitude of factors working against this. I'll readily admit that. Also remember, strong ULL can throw that cold enough in Boone comment out the window... They do weird/tricky things underneath them.

As Foothills & Marietta were mentioning with the 12Z GFS, it's leaving some southern stream energy behind, as the 0Z Euro did. This won't deepen the low nearly as much as previous runs! There is also some northern stream energy that doesn't get infused into this trough, so that's working against a stronger ULL as well. If it's not as strong, then all the snow talk can be thrown out the window .

There is a little hope though, weenie ideas I know , but at least it's pulled the ULL a little more to the east... That's certainly a trend worth watching over the next few days as we hone in on a solution.

[FoothillsNC]

I just cant see it snowing given those conditions and november climatology. If it's not cold enough to snow in Boone in November, it's not cold enough to snow anywhere in the lowlands.

There's been a few very small cold upper lows that missed Boone to the south, so while they were actually say +4 at 850 , it was snowing in Al, Ga and SC under -2 850 temps A strong closed off low can (and has ) make it snow under it and nw of its track. The new run of GFS doesnt' look much like its previous runs though, so who knows which way ECMWF will go.

[BullCityWx]

There's been a few very small cold upper lows that missed Boone to the south, so while they were actually say +4 at 850 , it was snowing in Al, Ga and SC under -2 850 temps A strong closed off low can (and has ) make it snow under it and nw of its track. The new run of GFS doesnt' look much like its previous runs though, so who knows which way ECMWF will go.

Oh, I believe it's possible, I'm just saying it's not likely.

[eyewall]

How much for Carrboro ?

[WeatherNC]

12z GFS = just another possible outcome, although we are taking a couple steps back, and look for the Euro to follow suit. 12z NAM @ 72 looks fairly similar to this morning's EC @ 84 in hanging some energy back over northern Mexico into the Baja. The issue starts to show up around 72hrs on this run of the GFS, and needs to be monitored as it prevents a more vigorous weakness at the base of the trough, which would allow the northern stream to really carve it out and cutoff in the MS/TN Valley. Southern stream energy will not be onshore in CA for another 24hrs, so we are looking at about 48hrs from now till a good UA sampling is done, and ingested. Also have to wonder since we are in that 5 day range, does the guidance start to back off, trend away from the extreme ULL solutions, only to see it reappear and verify in a somewhat watered down version of what was shown in the 5-7 day range.