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

[FoothillsNC]

GFS ensembles say that the Op is probably too fast, the Canadian sticking to its guns is a good sign. If the Ukie and Euro have a slower deeper trof, then maybe we will have something interesting. I find it interesting that the models are still this divergent only 96 hours out.

Same here, this is a very tough one. All the models are miles apart. The GGEM is now the most consistent but I've also seen it consistent and be wrong many times, so I'm not sure which way to lean. Some mix of all them might be the actual outcome, but it's hard for me to go against the GFS lately, and its' still matching SREF nicely. As much as I'd love the wild outcome, I'm probably leaning more progressive with a cutoff maybe developing over the srn.Apps or Carolinas piedmont somewhere, but don't have much confidence it that scenario either. The GFS has been painting a much colder pattern with strong shortwaves helping carve out a pretty deep trough in the midsection and east, meanwhile ECMWF still wants to keep it stormy out west, turning gradually colder about everywhere and it too builds enough ridging in the eastern Pacific to help deliver colder air into the country. The big thing is that it still looks stormy and very unsettled to say the least, with anything possible. Notice the GFS cutoffs again, those are still indicative of a pretty stormy pattern with wild changes. I'm still forecasting a better than average shot of a major snowstorm between the Plains and Apps and pretty far south, in December. Eventually, someone is going to really get dumped on with the white stuff. Meanwhile, more great weather here with rain every few days, a few cold mornings and nice afternoons. Perfect weather if you ask me.

One other thing the GGEM is still pretty far west down the front range with its northern stream digging, so if we're going to get a cutoff far to the south, thats the way to do it. Its possible and would fit the pattern (and the fact GFS shown it first...then lost it).

[oconeexman]

Same here, this is a very tough one. All the models are miles apart. The GGEM is now the most consistent but I've also seen it consistent and be wrong many times, so I'm not sure which way to lean. Some mix of all them might be the actual outcome, but it's hard for me to go against the GFS lately, and its' still matching SREF nicely. As much as I'd love the wild outcome, I'm probably leaning more progressive with a cutoff maybe developing over the srn.Apps or Carolinas piedmont somewhere, but don't have much confidence it that scenario either. The GFS has been painting a much colder pattern with strong shortwaves helping carve out a pretty deep trough in the midsection and east, meanwhile ECMWF still wants to keep it stormy out west, turning gradually colder about everywhere and it too builds enough ridging in the eastern Pacific to help deliver colder air into the country. The big thing is that it still looks stormy and very unsettled to say the least, with anything possible. Notice the GFS cutoffs again, those are still indicative of a pretty stormy pattern with wild changes. I'm still forecasting a better than average shot of a major snowstorm between the Plains and Apps and pretty far south, in December. Eventually, someone is going to really get dumped on with the white stuff. Meanwhile, more great weather here with rain every few days, a few cold mornings and nice afternoons. Perfect weather if you ask me.

One other thing the GGEM is still pretty far west down the front range with its northern stream digging, so if we're going to get a cutoff far to the south, thats the way to do it. Its possible and would fit the pattern (and the fact GFS shown it first...then lost it).

Agree with you Robert, going back to last year the GFS did a good job overall of picking up on these ULL and cut offs in the long range then losing them and bringing them back in mid range. The fine tuning part is pretty much a crap shoot imo. The canadian seems to always be too "wild" where the NAM seems to be too wet once in its range. i believe thats what makes us watching the developement of these storms so fun because very rarely do the computer models "nail" any storm...at least not all aspects of it. the GFS seems to be on to the stormy pattern and that tickles me for this time of year.

Happy Thanksgiving to all SE crew :thumbsup:

Now back to Packers/Lions and getting ready for nanner pudding

[WilkesboroDude]

Same here, this is a very tough one. All the models are miles apart. The GGEM is now the most consistent but I've also seen it consistent and be wrong many times, so I'm not sure which way to lean. Some mix of all them might be the actual outcome, but it's hard for me to go against the GFS lately, and its' still matching SREF nicely. As much as I'd love the wild outcome, I'm probably leaning more progressive with a cutoff maybe developing over the srn.Apps or Carolinas piedmont somewhere, but don't have much confidence it that scenario either. The GFS has been painting a much colder pattern with strong shortwaves helping carve out a pretty deep trough in the midsection and east, meanwhile ECMWF still wants to keep it stormy out west, turning gradually colder about everywhere and it too builds enough ridging in the eastern Pacific to help deliver colder air into the country. The big thing is that it still looks stormy and very unsettled to say the least, with anything possible. Notice the GFS cutoffs again, those are still indicative of a pretty stormy pattern with wild changes. I'm still forecasting a better than average shot of a major snowstorm between the Plains and Apps and pretty far south, in December. Eventually, someone is going to really get dumped on with the white stuff. Meanwhile, more great weather here with rain every few days, a few cold mornings and nice afternoons. Perfect weather if you ask me.

One other thing the GGEM is still pretty far west down the front range with its northern stream digging, so if we're going to get a cutoff far to the south, thats the way to do it. Its possible and would fit the pattern (and the fact GFS shown it first...then lost it).

Are we looking at advisory level snows for the mountains pretty much every run from the GFS, say Monday night?

[FoothillsNC]

Are we looking at advisory level snows for the mountains pretty much every run from the GFS, say Monday night?

I really haven't looked at the moisture fields yet but the GFS would have some decent snowshowers in the mtns, probably some down to GA border mtns and east TN with its setup. I don't see much of a way the higher mtns can escape seeing atleast some snow next week, either from the upslope wraparound or the cutoff at some point, but can't really say yet how much.

[Cheeznado]

Euro ensembles confirm my suspicions about the Op- that it is an outlier and too far south/southwest. Majority of the members have a closed low, consensus somewhere in the TN valley.

[SN_Lover]

According to the CMC, TN should get some snow from this!

[Reb]

According to the CMC, TN should get some snow from this!

does that deform band cross into eastern tennessee as well? that looks pretty yummy.

[FoothillsNC]

According to the CMC, TN should get some snow from this!

if the GGEM is right then the nw side would get a nice snowfall from this cutoff, but with all the scattering on this , its hard to trust it. It does lean heavily like the earlier GFS for sure, (and JMA) and would be a very big weather event with heavy rains and colder/snow underneath and nw side. A very well developed cutoff for sure.

[SN_Lover]

does that deform band cross into eastern tennessee as well? that looks pretty yummy.

This simulation does not go past 120 hours My best guess is yes. But we will have to wait for the 0Z run.

Here is the link: http://collaboration.cmc.ec.gc.ca/cmc/cmdn/pcpn_type/pcpn_type_gem_reg.html

[dsaur]

Same here, this is a very tough one. All the models are miles apart. The GGEM is now the most consistent but I've also seen it consistent and be wrong many times, so I'm not sure which way to lean. Some mix of all them might be the actual outcome, but it's hard for me to go against the GFS lately, and its' still matching SREF nicely. As much as I'd love the wild outcome, I'm probably leaning more progressive with a cutoff maybe developing over the srn.Apps or Carolinas piedmont somewhere, but don't have much confidence it that scenario either. The GFS has been painting a much colder pattern with strong shortwaves helping carve out a pretty deep trough in the midsection and east, meanwhile ECMWF still wants to keep it stormy out west, turning gradually colder about everywhere and it too builds enough ridging in the eastern Pacific to help deliver colder air into the country. The big thing is that it still looks stormy and very unsettled to say the least, with anything possible. Notice the GFS cutoffs again, those are still indicative of a pretty stormy pattern with wild changes. I'm still forecasting a better than average shot of a major snowstorm between the Plains and Apps and pretty far south, in December. Eventually, someone is going to really get dumped on with the white stuff. Meanwhile, more great weather here with rain every few days, a few cold mornings and nice afternoons. Perfect weather if you ask me.

One other thing the GGEM is still pretty far west down the front range with its northern stream digging, so if we're going to get a cutoff far to the south, thats the way to do it. Its possible and would fit the pattern (and the fact GFS shown it first...then lost it).

Gfs had another ULL at 300 something last night. As long as it keeps wanting to spin up some wandering mysteries we'll be trying to pin down mercury for the next month at least Tell you the truth I'm more hopeful at the rain chances than a chance at early, early snow. Always keeping in mind CR's coup from last year This pattern looks really good for filling up some creeks and lakes a bit. I'm starting to do much better down here, and just want to keep the short waves coming. The sleet/snow I want is the city stopping kind into fridged air, lol, and I can wait until the artic is upon us.

On tv GBurn's last night informed me we were in a strong Nina and it was going to be way warm all Dec. so my hopes are now really up for some major league cold before long, lol. T

[burgertime]

18z at 204 looks pretty durn good if you ask me.

[DaculaWeather]

On tv GBurn's last night informed me we were in a strong Nina and it was going to be way warm all Dec. so my hopes are now really up for some major league cold before long, lol. T

Well, cold for sure!

[FoothillsNC]

18z at 204 looks pretty durn good if you ask me.

Kinda reminds me of March 1993. The GFS is pretty good at seeing something big. But it's too far out. Lets see if the ECMWF follows its lead, or are we now at a time where the models reverse roles for the Winter months, and the GFS lives up to its old namesake. They're worlds apart. But both do have a super-active pattern, absolutely loaded, so I have zero doubt a mega storm is coming for some part of the country soon, and we're only growing colder.

[SN_Lover]

Gfs had another ULL at 300 something last night. As long as it keeps wanting to spin up some wandering mysteries we'll be trying to pin down mercury for the next month at least Tell you the truth I'm more hopeful at the rain chances than a chance at early, early snow. Always keeping in mind CR's coup from last year This pattern looks really good for filling up some creeks and lakes a bit. I'm starting to do much better down here, and just want to keep the short waves coming. The sleet/snow I want is the city stopping kind into fridged air, lol, and I can wait until the artic is upon us.

On tv GBurn's last night informed me we were in a strong Nina and it was going to be way warm all Dec. so my hopes are now really up for some major league cold before long, lol. T

Where is GBurn getting that from? We are in a weak to moderate La Nina.

KGSP-;"THE NAM/GFS/SREF ARE IN ONE CAMP WHICH BRING A PROGRESSIVE DEEP TROF INTO THE AREA BY SUNDAY. THE CANADIAN/ECMWF ARE MUCH SLOWER WITH THETROF AND BEGIN TO CLOSE OFF AN UPPER LOW AT THE BASE OF THE TROF BYTHE END OF THE PERIOD. THE FIRST GROUP BRINGS A COLD FRONT AND ITSASSOCIATED PRECIP INTO THE AREA SAT NITE AND MOVES IT WEST OF THECWFA BY AFTERNOON AS A DRY SLOT MOVES IN FROM THE WEST...LEAVINGONLY SOME LINGERING MTN PRECIP. THE SECOND GROUP...ON THE OTHERHAND...DOES NOT BRING THE FRONT AND THE BULK OF THE PRECIP IN UNTILSUN AFTERNOON. IN FACT...THE ECMWF IS SO SLOW THAT ONLY THE WRN CWFASEES ANY PRECIP BY SUN AFTERNOON. HAVE TRIED TO STRIKE A BALANCEBETWEEN THESE GROUPS...BUT IT IS TOO EARLY TO TELL WHICH SOLN ISBEST. WENT WITH LIKELY POP ACROSS THE WEST BY SUN MORN THEN SPREADTHE LIKELY POP ACROSS THE AREA DURING THE DAY. HAVE LOWS AROUND 10DEGREES ABOVE NORMAL SAT NITE AND HIGHS SUNDAY NEAR NORMAL EAST ANDA LITTLE BELOW NORMAL WEST."

[WeatherNC]

18z might be a small step in the right direction, 60hr panel is intriguing as it looks like it almost wants to close off at the base, note the bulging of the 546dm isohypse around Memphis...

[FoothillsNC]

18z might be a small step in the right direction, 60hr panel is intriguing as it looks like it almost wants to close off at the base, note the bulging of the 546dm isohypse around Memphis...

For a few runs a couple days ago, the GFS and GGEM both had an extremely sharp longwave with tons of vorts diving into it. In all the years I've followed 5h maps closely, I don't recall one quite as sharp, so thats why we were (are) getting the extreme cutoff ideas . I'd bet the models just aren't used to this and don't know how to portray such a longitudinal setup, the GGEM was just unbelievably sharp in its trough. So from a standpoint of pure meteorology this is fascinating and unknown (to me anyway). How to resolve it, no wonder we have the spread we do. I suppose anything from extreme cutoff to just a normal fropa is possible, even though the GFS was probably too unlikely from the start. If it reverts back tomorrow, we're in for a wild ride, and folks under the nw shield are in for their first good snow. The models still at this late run are showing a pretty good bit of northern stream energy diving due south, so more digging is probably coming. It may end up cutting off over eastern NC.

[WilkesboroDude]

18z GFS

Very good run for some to my west.

[DaculaWeather]

I now have loops of these http://www.daculaweather.com/gfs_18_500_vort_animated.php I like mine better (of course) than the NWS loops because they're smoother, gives me a better sense of motion.

[WeatherNC]

Yeah, pretty flipping impressive, just posted in the Nov thread, period around 12/1-12/3 needs to be watched, some long range rumblings we may see another storm.

[dsaur]

Where is GBurn getting that from? We are in a weak to moderate La Nina.

I hope it was just a slip of the tongue. I did yell at the tv but it never seems to do any good

T

[jrips27]

Yeah, pretty flipping impressive, just posted in the Nov thread, period around 12/1-12/3 needs to be watched, some long range rumblings we may see another storm.

I'll be in Gatlinburg, TN. 18z GFS at 204 would be might interesting... I've always heard that big storms can happen when the NAO goes from positive to negative, and that's exactly what happens on the GFS.

[griteater]

Late to the party, but interesting among all of the chaos that the Canadian had, essentially, 2 runs that had a very similar handling of the 500mb trough, with this morning's run being slightly stronger and colder.

The Euro is the only Op model that is progressive with the northern stream, and not phasing it with the southern parcel (did see where Cheez noted that Euro Ensemble Members where showing the cutoff solution, but not sure if that meant there was phasing).

From HPC:

BUT ALAS! EVERY OTHER PIECE OF NEW 12Z/24 GUIDANCE WAS

DRAMATICALLY SLOWER MOVING A CLOSED UPPER LOW ACROSS THE ERN/SERN

CONUS EARLY NEXT WEEK. THIS LED TO OUR SCRAPPING PRELIM CONTINUITY

AFTER SEEING THE 12Z/24 UKMET/CANADIAN/GEFS MEAN AND ECMWF. TURNS

OUT THAT THE 12Z GFS...WHILE BEING JUST 6 HOURS OF SO SLOWER THAN

ITS 00Z CONTINUITY MON/TUE WITH THE UPPER TROF AS IT APPROACHED

THE E COAST...WAS STILL A FAR NERN OUTLIER COMPARED TO THE REST OF

THE 12Z MODEL GUIDANCE. I ELECTED TO GO WITH 100% OF THE 12Z GEFS

ENSEMBLE MEAN WHICH WAS STILL WELL SW OF THE DETERMINISTIC GFS WIT

THE SYS BUT NE OF THE CANADIAN AND UKMET FORECASTS. THE 12Z ECMWF

IS ON THE FAR SW SIDE OF GUIDANCE.

[griteater]

For a few runs a couple days ago, the GFS and GGEM both had an extremely sharp longwave with tons of vorts diving into it. In all the years I've followed 5h maps closely, I don't recall one quite as sharp, so thats why we were (are) getting the extreme cutoff ideas . I'd bet the models just aren't used to this and don't know how to portray such a longitudinal setup, the GGEM was just unbelievably sharp in its trough. So from a standpoint of pure meteorology this is fascinating and unknown (to me anyway).

In late November 1952 there was a sharp trough, with strong cutoff low in the SE that produced 12 inches of snow in Knoxville... (correction - it was 18.2 inches of snow Nov 21-22)

[LithiaWx]

Kinda reminds me of March 1993. The GFS is pretty good at seeing something big. But it's too far out. Lets see if the ECMWF follows its lead, or are we now at a time where the models reverse roles for the Winter months, and the GFS lives up to its old namesake. They're worlds apart. But both do have a super-active pattern, absolutely loaded, so I have zero doubt a mega storm is coming for some part of the country soon, and we're only growing colder.

Wow Robert, those are some pretty impressive statements you just made. Coming from you I'm defintily taking note, amazing model runs to say the least. I know you have been beating the drum for a while about a major blizzard at some point in early winter, and when you now say zero doubt it makes me very excited even if it's not a GA storm when we get it. Asfor our ULL/cutoff it's going to be a late night of wating for the Euro for me.

[Solak]

Got to love this line from RAH's afternoon discussion after a good in depth overview of the model differences.

"BOTTOM LINE IS... MINIMAL CHANGES TO THE FORECAST DUE TO NO CONFIDENCE IN BEING ABLE TO IMPROVE IT."

[ST21]

Wow Robert, those are some pretty impressive statements you just made. Coming from you I'm defintily taking note, amazing model runs to say the least. I know you have been beating the drum for a while about a major blizzard at some point in early winter, and when you now say zero doubt it makes me very excited even if it's not a GA storm when we get it. Asfor our ULL/cutoff it's going to be a late night of wating for the Euro for me.

With the way the models have handled this storm, I'm prepared for the extremes.

[SN_Lover]

0Z GFS

Hr(s) 57 ->93 : No ULL for SE ; Run not as good as 18Z

crossing my fingers for the Euro.

[griteater]

NAM and GFS in with a frontal passage = swath of rain followed by upslope flakes in E TN / NC Mtns

[WeatherNC]

0z GGEM, 548 close off in northern MS @ 72, 541 H5 bowling ball, neg tilt, central AL 84 hrs

Edit, 538 just sw of ATL at day 4

[Gastonwxman]