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

[WeatherNC]

00z GFS is coming in farther north

Hard to say as it opens up after 108 over the GL, and still a stout vort neutral'ish tilt around the mouth of the MS @ 117.

[griteater]

00z GFS is coming in farther north

Well, it didn't end up north.

for TN

[jrips27]

It looks to me like the 0z came in a tad south and a bit quicker. As much as 4" of snow in TN

Through 156

[WeatherNC]

Well, it didn't end up north.

Wow! Have fun with this guys, and gals

150 panel, straight p&%$ considering late Nov

<540 heights, maybe some convective type squalls, north, east, south and west of the center, token inch or two

[LithiaWx]

Oh my goodness... The 0Z GFS is awesome! This run the cold settles in behind the front and ULL and sticks around for a little while. Also dropping light amounts of snow in many places in the southeast. If this run verified verbatim there would be flakes flying for lots of us. Pure porn for November in the Deep South...

Sounding for Marietta, GA at hour 150.. With light precip in the area...

[CAD_Wedge_NC]

Wait until Foothills sees this run........He looks to be right about this storm changing the pattern, I would love to be in the mountains for this one.

[griteater]

[griteater]

[jrips27]

Wow 0z GFS is brrrr for the rest of the run!! Good news!

Day 6-10 Temp Anomalies

Day 11-15 Temp Anomalies

[WilkesboroDude]

This run is looking much better for North Carolina. Maybe we see something light instead of nothing.

First small spill over east of the mountains?

[dsaur]

That looks about right to me I've gotten over 8 inches from two ULL's, at almost spring, in the last 3 years, no reason to think this couldn't happen in fall....except maybe climo, lol. T

[CAD_Wedge_NC]

Oh my goodness... The 0Z GFS is awesome! This run the cold settles in behind the front and ULL and sticks around for a little while. Also dropping light amounts of snow in many places in the southeast. If this run verified verbatim there would be flakes flying for lots of us. Pure porn for November in the Deep South...

Sounding for Marietta, GA at hour 150.. With light precip in the area...

That's definately a snow sounding....saturation all the way up to 500mb and 800mb temps at -10c. Surface temps near 0c. Looks more like a sounding you might see in January.

[Gastonwxman]

It's interesting of how long this scenario has been indicated. Usually you would see this kind of threat go poof in a day or two but the closer we get, the more it's beginning to look as though a "white end" to this month is in store. Of course, we still have up until the weekend to see if it holds but I'm liking our chances for parts of the Southeast. You've got nice wrap-around 7H moisture to work with the cold core to produce some light snow showers/flurries across certain areas. Fun times ahead. Can't wait to see how the Euro handles this.

[griteater]

UKMet and Canadian both way north with merely a frontal passage through the southeast states. Canadian deposits the southern piece of energy in Texas.

GFS still on an island.

[WilkesboroDude]

Can someone gently nudge the cutoff low a little to the east for next week?

[LithiaWx]

UKMet and Canadian both way north with merely a frontal passage through the southeast states. Canadian deposits the southern piece of energy in Texas.

GFS still on an island.

I don't think the Canadian has ever shown a cutoff for this storm. The UKMet I have not been following closely enough to see if it has waffled or not. The Euro has shown the cutoff scenario a few times and a few of them looked a lot like this GFS run. Battle of the models it seems. The GFS has been pretty darn persistent with this idea in one form or another.

[Cheeznado]

UKMet and Canadian both way north with merely a frontal passage through the southeast states. Canadian deposits the southern piece of energy in Texas.

GFS still on an island.

Huge spread in the GFS ensembles after Saturday- this could do almost anything. Almost impossible medium range forecast.

[LithiaWx]

Huge spread in the GFS ensembles after Saturday- this could do almost anything. Almost impossible medium range forecast.

Just curious, where do you get individual ensemble images this soon?

[Cheeznado]

Just curious, where do you get individual ensemble images this soon?

Have a spaghetti plot from WSI, not available to the public.

[griteater]

I don't think the Canadian has ever shown a cutoff for this storm. The UKMet I have not been following closely enough to see if it has waffled or not. The Euro has shown the cutoff scenario a few times and a few of them looked a lot like this GFS run. Battle of the models it seems. The GFS has been pretty darn persistent with this idea in one form or another.

Last night's Canadian was way south with closed low over north Bama / GA. A few runs back the UKMet was way south as well.

[Cheeznado]

00Z Euro closes off a low in northern MS at 132, but a lot weaker than the GFS. The Ukie is farther west but also weaker than the GFS, but a bit stronger than the Euro.

EDIT: Tuesday AM 543 DM 500mb low just west of ATL, would be some snow here

[Gastonwxman]

Figured I post this. For KCLT on Tuesday 8am per 0z GFS at 156:

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Precip. type with 2m temperature:

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[LithiaWx]

00Z Euro closes off a low in northern MS at 132, but a lot weaker than the GFS. The Ukie is farther west but also weaker than the GFS, but a bit stronger than the Euro.

EDIT: Tuesday AM 543 DM 500mb low just west of ATL, would be some snow here

Very Nice! This is very exciting stuff to be tracking in late November.

[CandymanColumbusGA]

I'm surprised none of you have picked up on what the Euro is saying...

It has the cut-off low over Montgomery/Columbus by Monday afternoon, with more a neutral tilt... This would send snow across portions of N GA/ N AL/Western Carolinas... Hell! It might even bring flurries to Columbus Monday night....

After the low sits over Atlanta for a while, it finally ejects toward the Carolinas and up the coast, but another piece of energy starts rotating around it... This could bring another shot of cold and maybe a few more flurries for some by the end of next week...

Others with a bit more time can provide further detail, but the EURO is now SOUTH of the GFS. Certainly a trend many of you want to see!

Certainly going to be an interesting time while I'm on the beach in Florida!!! You're welcome hahahah!

[FoothillsNC]

The possibilities of anything are still on the table but today we'll start to narrow it down. To me the GFS still looks a little too extreme, and even though it fits the pattern to have something like that, I'm not too enthused that this is going to be a big win for it yet. The ecmwf has comes to a cutoff even though it probably drops too much energy in the Southwest. Thats where the big difference lies in the 2, and now the GGEM looks closer to it than GFS. Notice how the southern trough gets mostly cutoff in the southwest :

Earlier the models, esp. GFS were insisting that all the energy from the northern stream drops due south along the front range of the Rockies to help form the extreme low lat. cutoff, but that's going to be hard to do. It would require enormous ridging in the east Pac or British Columbia and I don't quite see that yet , and it would be incredibly rare to get a cutoff so deep and far south (but if any year could do it, this is the one). We may end up with something more like ECMWF and a watered down version of GFS, with partial phasing of northern stream. That scenario would be warmer under the cutoff. By the way, the GFS would still be hard to snow in the lower elevations east of the mtns , remember there's usually a warm bubble east of the mountains unless high pressure is pushing south on both sides of the Apps, so I don't see this as March 2009. Soundings right now would lead you astray east of the Apps since the models almost always make it too cold east of the Apps in this situation. But believe it or not major snow is possible on the nw side of the low whereever that ends up being, can't say yet, but if a deep cutoff happens this far south, then Tenn and surrounding areas from Apps, west are possible, including ATL and HSV. The ECMWF isn't that cold though, but gets very close, even without it fully phasing the northern stream. If the northern stream comes in like the sudden injection GFS has been having, some -4 at 850 would be good enough at night and early mornings for the flakes to fall, but so far no model has a lot of moisture or lift underneath the best cold air (except maybe GFS has a weak deformation type band or moisture convergence in nw side).

The biggest deal still could be the high winds, a possible well developed LLJ which models still don't show or bring to surface but if a Full-Lat trough occurs and reaches the Gulf Coast, I think they will start to show it. Severe line also, esp. once the system begins cutting off, which would develop a south to north line of severe, and including heavy rain threat to the Apps and western Carolinas and ATL AHN region of GA to the Apps. Strong southeast upslope would occur in the mtns esp NC and ne GA mtns with the GFS setup, producing 5" of rain easily, with much more in the sw mtns of NC if the system stalls like GFS, but can't say for sure. One thing about the rain rates, they will be high if the GFS is right on the sharpness of the trough. Maybe .50" to .75" per hour in an a band directly along the mid level front in the Gulf region, from east Tx to La and central /N. Mississipp, that could carry east as the line expands. That would be flash type flooding. Here's just a 6 hour window as it begins, but models probably under-do the rates on a super-sharp trough this far south.

So we're entering an even harder time to forecast than what we've just been through, and that's saying a lot. Does the pattern change to colder like GFS has? Maybe, but if its wrong on this cutoff too much, then maybe not much of a colder pattern. But all models seem to be showing a weak western ridge + PNA pattern so I think we probably will get into colder pattern. But there still no shortage of energy in the flow and cutoff's galore. That could make for a continuation of this extremely active pattern. Its been a strange pattern for a NINA. Already I'm about normal for the year's rainfall, not below. Some parts of the county are already above for the year, with a solid month to go, guaranteeing an above normal rainfall year. For a year that was in solid Nina mode, and a hot Summer, that's pretty surprising and I never would have dreamed that just a year ago...I've had about as much rain as some el Nino patterns could do.

[rosie]

Monday Night...Mostly cloudy with a 30 percent chance of rain or snow showers. Windy. Lows in the lower 30s.

[FoothillsNC]

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:

[msuwx]

The 6z GFS is simply jaw-dropping to watch. Such an extreme solution, but really, I would not be shocked to see something fairly similar to this occur.....maybe not quite as extreme.

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Really, the Euro is extremely similar, just not quite as intense as the GFS, mainly because it drops a piece of energy from the tail end of the trough back into old Mexico.

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:

[HWY316wx]

The possibilities of anything are still on the table but today we'll start to narrow it down. To me the GFS still looks a little too extreme, and even though it fits the pattern to have something like that, I'm not too enthused that this is going to be a big win for it yet. The ecmwf has comes to a cutoff even though it probably drops too much energy in the Southwest. Thats where the big difference lies in the 2, and now the GGEM looks closer to it than GFS. Notice how the southern trough gets mostly cutoff in the southwest :

Earlier the models, esp. GFS were insisting that all the energy from the northern stream drops due south along the front range of the Rockies to help form the extreme low lat. cutoff, but that's going to be hard to do. It would require enormous ridging in the east Pac or British Columbia and I don't quite see that yet , and it would be incredibly rare to get a cutoff so deep and far south (but if any year could do it, this is the one). We may end up with something more like ECMWF and a watered down version of GFS, with partial phasing of northern stream. That scenario would be warmer under the cutoff. By the way, the GFS would still be hard to snow in the lower elevations east of the mtns , remember there's usually a warm bubble east of the mountains unless high pressure is pushing south on both sides of the Apps, so I don't see this as March 2009. Soundings right now would lead you astray east of the Apps since the models almost always make it too cold east of the Apps in this situation. But believe it or not major snow is possible on the nw side of the low whereever that ends up being, can't say yet, but if a deep cutoff happens this far south, then Tenn and surrounding areas from Apps, west are possible, including ATL and HSV. The ECMWF isn't that cold though, but gets very close, even without it fully phasing the northern stream. If the northern stream comes in like the sudden injection GFS has been having, some -4 at 850 would be good enough at night and early mornings for the flakes to fall, but so far no model has a lot of moisture or lift underneath the best cold air (except maybe GFS has a weak deformation type band or moisture convergence in nw side).

The biggest deal still could be the high winds, a possible well developed LLJ which models still don't show or bring to surface but if a Full-Lat trough occurs and reaches the Gulf Coast, I think they will start to show it. Severe line also, esp. once the system begins cutting off, which would develop a south to north line of severe, and including heavy rain threat to the Apps and western Carolinas and ATL AHN region of GA to the Apps. Strong southeast upslope would occur in the mtns esp NC and ne GA mtns with the GFS setup, producing 5" of rain easily, with much more in the sw mtns of NC if the system stalls like GFS, but can't say for sure. One thing about the rain rates, they will be high if the GFS is right on the sharpness of the trough. Maybe .50" to .75" per hour in an a band directly along the mid level front in the Gulf region, from east Tx to La and central /N. Mississipp, that could carry east as the line expands. That would be flash type flooding. Here's just a 6 hour window as it begins, but models probably under-do the rates on a super-sharp trough this far south.

So we're entering an even harder time to forecast than what we've just been through, and that's saying a lot. Does the pattern change to colder like GFS has? Maybe, but if its wrong on this cutoff too much, then maybe not much of a colder pattern. But all models seem to be showing a weak western ridge + PNA pattern so I think we probably will get into colder pattern. But there still no shortage of energy in the flow and cutoff's galore. That could make for a continuation of this extremely active pattern. Its been a strange pattern for a NINA. Already I'm about normal for the year's rainfall, not below. Some parts of the county are already above for the year, with a solid month to go, guaranteeing an above normal rainfall year. For a year that was in solid Nina mode, and a hot Summer, that's pretty surprising and I never would have dreamed that just a year ago...I've had about as much rain as some el Nino patterns could do.

Great write up Robert! As always!

[Lookout]

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?