SE Mid-Long Range Discussion

[GaWx]

Hey, I'm just curious. Do you know when the last time Atlanta officially had a 6" inch or greater snowstorm ? It seems like forever. I mean I know Atlanta isn't a snowy city by any means, but you would think some random freakish snowstorm would give Atlanta a big snowstorm once in a blue moon.

They have:

1)KATL got 7.9" of very wet S 3/24/1983.

2)KATL: got 7.0" of S/IP 1/12-14/1982 from two separate Gulf sfc lows (the infamous snowjam, which I'll never forget, over an extremely cold ground..city closed down for many days!).

North ATL did get 6"++ of S in the 3/13/1993 blizzard.

One of the reasons KATL doesn't get as many 6" snows is that IP often mixes in thus reducing ratios. Actually, the 1/1988 and 2/1979 were massive in their own right with each producing 4.2" of mainly IP!! Either of those was easily wet enough to produce 6"+ of snow. Keep in mind that 4" of IP is way more sig. and has much more of an impact/longer lasting than 6" of snow, regardless. 4" of IP is about equiv. to a foot of snow. So, it is deceiving to not think of these two 4.2" mainly IP storms as not being two of the greatest ATL storms of the 20th century.

The 1/22/1987 storm produced 3.6" of S at KATL from 0.75" of liquid. In this case, the snow mixed with or changed to rain at times. So, if it had been colder, this also would have been wet enough to produce 6" of S at KATL. I got nearly 5" of S in Doraville.

All of these storms were Gulf based, of course.

[Snowless in Carrollton]

They have:

1)KATL got 7.9" of very wet S 3/24/1983.

2)KATL: got 7.0" of S/IP 1/12-14/1982 (the infamous snowjam, which I'll never forget, over an extremely cold ground..city closed down for many days!).

North ATL did get 6"++ of S in the 3/13/1993 blizzard.

One of the reasons KATL doesn't get as many 6" snows is that IP often mixes in thus reducing ratios. Actually, the 1/1988 and 2/1979 were massive in their own right with each producing 4.2" of mainly IP!! Either of those was easily wet enough to produce 6"+ of snow. Keep in mind that 4" of IP is way more sig. and has much more of an impact/longer lasting than 6" of snow, regardless. 4" of IP is about equiv. to a foot of snow. So, it is deceiving to not think of these two 4.2" mainly IP storms as not being two of the greatest ATL storms of the 20th century.

The 1/22/1987 storm produced 3.6" of S at KATL from 0.75" of liquid. In this case, the snow mixed with or changed to rain at times. So, if it had been colder, this also would have been wet enough to produce 6" of S at KATL. I got nearly 5" of S in Doraville.

All of these storms were Gulf based, of course.

Amazing that it's been nearly 30 years since the Atlanta airport has had 6" + snow. When you look at other southern cities ( Dallas, Birmingham, Nashville, Charlotte), they seem to all have had 6" snowfalls in the last 20 years. Why is it so hard for Atlanta to get a huge snowfall ?

[GaWx]

Amazing that it's been nearly 30 years since the Atlanta airport has had 6" + snow. When you look at other southern cities ( Dallas, Birmingham, Nashville, Charlotte), they seem to all have had 6" snowfalls in the last 10 years. Why is it so hard for Atlanta to get a huge snowfall ?

Read my post again. Did you read it all?

Edit: comparing ATL to Nashville and Charlotte is not fair since they are a good bit further north.

[Met1985]

Looks like there could be a very strong SE ridge building in for the upcoming week. Does not look good to any cold air at all currently but i am sure the models with change but also the AO and NAO are looking to stay very positive and the PNA looks to dip negative and that may pump up the ridge. if i am looking at this wrong please let me no thanks.

[Cold Rain]

Good point about NC vs. GA. Yes, I have a GA (ATL/SAV) perspective and much of NC gets more wintry precip. most years. Also, I already admitted that the high mountain areas are an exception to the rather infrequent winter precip. locations in the SE. However, isn't it true even up at RDU that a strong majority of Dec.-Mar. precip. isn't wintry?

Yep. And this goes back to something that I was saying the other day. Sometimes we tend to get discouraged when we see a met or knowledgeable source posting probabilities of the AO or NAO staying positive or the MJO dying in phase 4 or something like that. We get discouraged that Winter is over. But if we saw the probabilities of winter precip events in D-F in relation to all precip events, we'd probably be discouraged about that. I'd imagine it's pretty low in places like RDU, ATL, CLT, etc....

The point is, in this part of the country, overwhelming cold has it's own problems generating wintry precip. So does sustained warm. So does intermittent warm/cold. It all comes down to timing down here. There is plenty of cold in Canada. We're seeing HP drop down into the plains and translate eastward. We have an active suptropical jet. There's a recurring SE ridge right now, but good timing can still produce a widespread winter event, even though the probabilities of an AO- and NAO- are low for the near term.

[burgertime]

Yep. And this goes back to something that I was saying the other day. Sometimes we tend to get discouraged when we see a met or knowledgeable source posting probabilities of the AO or NAO staying positive or the MJO dying in phase 4 or something like that. We get discouraged that Winter is over. But if we saw the probabilities of winter precip events in D-F in relation to all precip events, we'd probably be discouraged about that. I'd imagine it's pretty low in places like RDU, ATL, CLT, etc....

The point is, in this part of the country, overwhelming cold has it's own problems generating wintry precip. So does sustained warm. So does intermittent warm/cold. It all comes down to timing down here. There is plenty of cold in Canada. We're seeing HP drop down into the plains and translate eastward. We have an active suptropical jet. There's a recurring SE ridge right now, but good timing can still produce a widespread winter event, even though the probabilities of an AO- and NAO- are low for the near term.

For CLT in Dec. it's always a I-40 N storm. Last year when we had the good setup and the first big winter storm rolled through it was like 34 and rain here in CLT. So even with favorable conditions for December CLT still has a very hard time getting wintry precip in Dec. We did get the Christmas miracle, but it was only so special because it happened for the first time in 44 years which tells you something.

[WeatherNC]

Yes CR they are low, rough balling this am, RDU avgs about 7.5" of SN a year, CLT 5.1, for Raliegh, avg precip in the D-F period is 14.5", throw in a straight 10:1 for SN, maybe another half-three quarters for frozen not otherwise covered, and about, or less than 10% of precip during this period is of the winter type.

That was a good post, overwhelming cold has it problems, recently southern sliders through the FL peninsula in the extreme sense. However, a pattern that basically shuts the NE out, cold and dry, can pay dividends for the SE as we are usually the battle ground between moisture, and sustained cold just to our north. The setup cannot be ignored, and when one looks for the favorable players to be on the field, and they are not, it is hard to get excited about anything sig materializing in the near future.

The MJO is a valuable tool imo, obviously not absolute, but historically certain phases have corresponded to more favorable conditions in the east in terms of winter wx. Don S AO stuff is also a great read, and would imply less overall chances of the eastern half of CONUS flipping to a colder pattern, at-least for the second half of Dec, maybe into Jan too. Sure there will be chances, but they are likely to be fewer and far between. Living in the SE we only get a couple chances at the plate every year, and it sure is better going in with a clean count compared to already having a strike or two against you, which we have currently.

[nchighcountrywx]

Bastardi Weatherbell Subscribers: Check Joe's latest discussions:

Bastardi today talks of the start of a stratospheric warming event beginning in Siberia in about 10 days similar to 84/85 that could be a 2-3 week precursor to major cold in the US.

[GaWx]

Yes CR they are low, rough balling this am, RDU avgs about 7.5" of SN a year, CLT 5.1, for Raliegh, avg precip in the D-F period is 14.5", throw in a straight 10:1 for SN, maybe another half-three quarters for frozen not otherwise covered, and about, or less than 10% of precip during this period is of the winter type.

That was a good post, overwhelming cold has it problems, recently southern sliders through the FL peninsula in the extreme sense. However, a pattern that basically shuts the NE out, cold and dry, can pay dividends for the SE as we are usually the battle ground between moisture, and sustained cold just to our north. The setup cannot be ignored, and when one looks for the favorable players to be on the field, and they are not, it is hard to get excited about anything sig materializing in the near future.

The MJO is a valuable tool imo, obviously not absolute, but historically certain phases have corresponded to more favorable conditions in the east in terms of winter wx. Don S AO stuff is also a great read, and would imply less overall chances of the eastern half of CONUS flipping to a colder pattern, at-least for the second half of Dec, maybe into Jan too. Sure there will be chances, but they are likely to be fewer and far between. Living in the SE we only get a couple chances at the plate every year, and it sure is better going in with a clean count compared to already having a strike or two against you, which we have currently.

Good post.

1) Ok, so ~10% liquid equiv. at RDU is wintry vs. ~4% at ATL. So, not surprisingly a much higher at RDU (more than double), but still pretty low.

2) For Atl., best chances at a major S/IP by far occur when a Miller A forms off of central or south TX and moves ENE to anywhere from the FL Panhandle/far S GA to as far south as central FL pen. (say Tampa to Daytona). For Sav., best chances are when Miller A moves over C or S FL.

The NE has gotten little or nothing from, perhaps, about half (just wild guessing on this) of the major ATL S/IP's whereas they've been shutout on just about all of the sig. SAV wintry events.

3) I recently posted about the implications of MJO stage on the chance of a major S/IP event at ATL and found no better than a very weak correlation. However, I did find a pretty good partial correlation of a -NAO

(and I assume -AO) with that. Also, even a +PDO was found to have a halfway decent partial correlation. So, for ATL major S/IP chances, NAO/AO and even PDO have more predictive value than the not so helpful

MJO stage. Now, regarding major Atl. ZR, it is a different story.

[FoothillsNC]

Looks like there could be a very strong SE ridge building in for the upcoming week. Does not look good to any cold air at all currently but i am sure the models with change but also the AO and NAO are looking to stay very positive and the PNA looks to dip negative and that may pump up the ridge. if i am looking at this wrong please let me no thanks.

The big heat in NC is in big trouble for NC this week (and beyond) . First we have damming Tomorrow and Tuesday and even in Wednesday theres new High Pressure ridging down from Canada, so definitely the first half of the week is not warm at all. It will take until very late Thursday or maybe Friday before the next front can pull in southwest flow and that should be tempered by cloud cover and rain. So not looking like a sunny warm week here. And pretty quickly the next southern stream system is coming our way, and new high pressure sprawls behind the front and is about to ridge down once again. More rain quickly on the heels of the Friday front, and I would'nt be surprised to see our area actually below normal mostly over the next week. I keep on seeing quite a bit of high pressure to the north, damming, lots of clouds and occasional precip here. I'm glad I distanced myself back in November from trying to twist a forecast around an AO or NAO state alone, because that methodology defies what's currently happening. Its' all about the pattern. I begin by looking out my window...not looking on a chart.

[dsaur]

Hey, I'm just curious. Do you know when the last time Atlanta officially had a 6" inch or greater snowstorm ? It seems like forever. I mean I know Atlanta isn't a snowy city by any means, but you would think some random freakish snowstorm would give Atlanta a big snowstorm once in a blue moon.

One of the most successful random, freakish, frozen precip. storms I ever saw in Atl. was the ice storm in the early 70's. Not a whole lot of that went to waste. Inches + of zrain. Usually in Atl., because we don't have mtns. for lift, we are relying of transport from the gulf for our big storms, and that means warmth is a part of the mix. We lose a lot of snow to rain, to sleet, to zrain, as Larry said, and if a huge snow dump takes place, often is is wet snow onto warm ground. As Larry will tell you we want a moderate storm not a strong storm for out best chances. That means less rain but more cold on average, plus we want a track through Fla. so we aren't too near the heat and the cold can ooze down further...but then the fat rain chances move further south.

Then there is the airport, where official totals are gathered, which often has a climate all to it's own I sometimes get more than the airport, I sometimes get less. I'm closer to the moisture, but closer to the heat. I think, on average, given a choice, I'd take where I am now for frozen events, over midtown, and Buckhead, where I lived in Atl.. I'd also take where you are, over Atl. Just because the airport doesn't register much doesn't mean there aren't kids of all ages somewhere in Ga. piling up memories. I got a few inches from the blizzard, and I have friends that lived along the Hooch that had well over a foot. About equal distance from the airport....just all depends on where your live, and the vagaries of the storm....it was equally fearce here...just didn't dump as much moisture, though I still had white out conditions.

That 7.9 inch storm at the airport that Larry mentioned, gave me well over 10" down here.....most snow I've seen in a Ga. storm. Might have been near twice that if it had been much colder.

And look at the bowling ball that rolled through Macon with 16"+. The Atl. airport didn't get squat. Vagaries, pesky vagaries, lol. T

[Met1985]

The big heat in NC is in big trouble for NC this week (and beyond) . First we have damming Tomorrow and Tuesday and even in Wednesday theres new High Pressure ridging down from Canada, so definitely the first half of the week is not warm at all. It will take until very late Thursday or maybe Friday before the next front can pull in southwest flow and that should be tempered by cloud cover and rain. So not looking like a sunny warm week here. And pretty quickly the next southern stream system is coming our way, and new high pressure sprawls behind the front and is about to ridge down once again. More rain quickly on the heels of the Friday front, and I would'nt be surprised to see our area actually below normal mostly over the next week. I keep on seeing quite a bit of high pressure to the north, damming, lots of clouds and occasional precip here. I'm glad I distanced myself back in November from trying to twist a forecast around an AO or NAO state alone, because that methodology defies what's currently happening. Its' all about the pattern. I begin by looking out my window...not looking on a chart.

Thanks Foothills for clarifying what is really going on. This is my first year of really getting into the weather models and keeping an eye on them but i have recently been to involved in them instead of just looking out the window and seeing what may really happen oppose to what the models are saying. Thanks for writting about my post and i keep learning something new from you and all the other people on the boards!

[BullCityWx]

I think this thread should be locked until there is some sign at all that the pattern will change.

[SnowDeac]

I think this thread should be locked until there is some sign at all that the pattern will change.

I think you should be locked from posting. No one's forcing you to look at it. If someone changed it to "Long Range Forecast", would it really make you that much happier? Sorry, but your posts on this thread have been annoyingly negative and pointless. There has been a lot of solid discussion about a proposed patter change/lack thereof and the reasoning behind each line of thought.

[beanskip]

Careful there, friend.

QueenCity is a longtime poster who has proven his ability to add value to the conversation, his last post notwithstanding.

Truthfully, I am more annoyed by unrealistic optimism than by his frank realism. The truth is, there is really zero sign of the pattern changing anytime soon. To have a thread devoted to something that is not happening on our side of the horizon is rather silly.

I also find the arguments about where we end up relative to normal rather pointless. Most folks don't frequent these boards because they are "below normal" lovers, but because they are winter weather lovers.

Yeah, it's not really that warm right now. But without the chance of snow, that's a moot point to me.

I think you should be locked from posting. No one's forcing you to look at it. If someone changed it to "Long Range Forecast", would it really make you that much happier? Sorry, but your posts on this thread have been annoyingly negative and pointless. There has been a lot of solid discussion about a proposed patter change/lack thereof and the reasoning behind each line of thought.

[WSNC]

Latest from Larry Cosgrove. Sorry if already posted. This is not the first I've read about a possible upcoming SSW event that could force the polar vortex south/turn the AO negative. It's my understanding that the cold outbreak in NA when/if the AO finally turns negative could be historic due to the incredible build up of cold air in the North Pole during the recent historic positive phase of the AO.

EXTENDED PERIOD FORECAST

(Between Day 11 And Day 15)

"Life After The Storm": Why The Circumpolar Vortex Bodes Ill For Those Hating The Cold!

NOAA/SSD/IMS

NRL

WEATHERAmerica

Environment Canada

Penn State University E-Wall

There are three key features which may or may not impact the longer term outlook. One, of course, is the S FL/Bahamas heat ridge that is forecast to flatten/weaken somewhat. Another is the potential major winter storm (aided by inflow from the Pacific Ocean subtropical jet stream) slated to affect much of the nation through December 21 (see attached image). But the big player in the system is the cAk motherlode, also known as the Circumpolar Vortex. Many of the numerical models have been suggesting that this feature, until recently stuck near the North Pole, may drift and expand southeastward with a core position near Hudson Bay.

The recent tendency for full-phase, massive bombogenesis cases in the northern Atlantic Ocean might be explained by this drift, which is essentially a case of a positive phase of the Arctic Oscillation gone insane. So much cold air in a cluster starts to "drip" over the pole into North America. In time breakaway pieces from the gyre drag the core circulation so far south that pure cAk values are able to occupy locations in the U.S. This type of event has happened twice in recent history: December 1976/January 1977 and December 1983. Once established, the dome can last as much as 45 days, destroying temperature records in the process. It is too early to suggest that this scenario might verify, but recent stratospheric temperature anomaly forecasts are turning very warm over Canada in the 11 - 15 day period. If so, southward displacement of the harshest of air mass may be enabled in the days just before Christmas.

[Brick Tamland]

I just read Allan Huffman's latest blog post and I am getting excited. It all depends on the timing, but at least there are a few chances to keep watch on this weekend and headed into Christmas.

http://www.examiner.com/weather-in-raleigh/any-wintry-weather-possibilities-ahead-for-the-southeast

[LithiaWx]

Latest from Larry Cosgrove. Sorry if already posted. This is not the first I've read about a possible upcoming SSW event that could force the polar vortex south/turn the AO negative. It's my understanding that the cold outbreak in NA when/if the AO finally turns negative could be historic due to the incredible build up of cold air in the North Pole during the recent historic positive phase of the AO.

EXTENDED PERIOD FORECAST

(Between Day 11 And Day 15)

"Life After The Storm": Why The Circumpolar Vortex Bodes Ill For Those Hating The Cold!

NOAA/SSD/IMS

NRL

WEATHERAmerica

Environment Canada

Penn State University E-Wall

There are three key features which may or may not impact the longer term outlook. One, of course, is the S FL/Bahamas heat ridge that is forecast to flatten/weaken somewhat. Another is the potential major winter storm (aided by inflow from the Pacific Ocean subtropical jet stream) slated to affect much of the nation through December 21 (see attached image). But the big player in the system is the cAk motherlode, also known as the Circumpolar Vortex. Many of the numerical models have been suggesting that this feature, until recently stuck near the North Pole, may drift and expand southeastward with a core position near Hudson Bay.

The recent tendency for full-phase, massive bombogenesis cases in the northern Atlantic Ocean might be explained by this drift, which is essentially a case of a positive phase of the Arctic Oscillation gone insane. So much cold air in a cluster starts to "drip" over the pole into North America. In time breakaway pieces from the gyre drag the core circulation so far south that pure cAk values are able to occupy locations in the U.S. This type of event has happened twice in recent history: December 1976/January 1977 and December 1983. Once established, the dome can last as much as 45 days, destroying temperature records in the process. It is too early to suggest that this scenario might verify, but recent stratospheric temperature anomaly forecasts are turning very warm over Canada in the 11 - 15 day period. If so, southward displacement of the harshest of air mass may be enabled in the days just before Christmas.

http://www.americanw...78#entry1186678

There are mets and good posters who don't buy the SSW and think it's hype. I guess what I'm saying is it's far from a clear signal.

[NCStateMMY]

Good post.

1) Ok, so ~10% liquid equiv. at RDU is wintry vs. ~4% at ATL. So, not surprisingly a much higher at RDU (more than double), but still pretty low.

2) For Atl., best chances at a major S/IP by far occur when a Miller A forms off of central or south TX and moves ENE to anywhere from the FL Panhandle/far S GA to as far south as central FL pen. (say Tampa to Daytona). For Sav., best chances are when Miller A moves over C or S FL.

The NE has gotten little or nothing from, perhaps, about half (just wild guessing on this) of the major ATL S/IP's whereas they've been shutout on just about all of the sig. SAV wintry events.

3) I recently posted about the implications of MJO stage on the chance of a major S/IP event at ATL and found no better than a very weak correlation. However, I did find a pretty good partial correlation of a -NAO

(and I assume -AO) with that. Also, even a +PDO was found to have a halfway decent partial correlation. So, for ATL major S/IP chances, NAO/AO and even PDO have more predictive value than the not so helpful

MJO stage. Now, regarding major Atl. ZR, it is a different story.

Another reason for RDU's higher average amounts of wintry precip appears to be the more baroclinic interaction of storm systems in this region. When you look back at the rcords for large precipitation events, winter storms and tropical systems included, you see tha it is not an even distribution of precipitation over the Piedmont and coastal plain. There are relativly narrow strips of heavey accumulations, with modertate to light accum 25-50 miles either side of these areas. You can see that on the accum maps for these storms:

http://www4.ncsu.edu/~nwsfo/storage/cases/20101226/accum.20101225.and.20101226.separate.gif

http://www4.ncsu.edu/~nwsfo/storage/cases/20041226/

http://www4.ncsu.edu/~nwsfo/storage/cases/20020102/

http://www4.ncsu.edu/~nwsfo/storage/cases/20000125/

http://www4.ncsu.edu/~nwsfo/storage/cases/19990915/

http://www4.ncsu.edu/~nwsfo/storage/cases/19990915/

So in some respects, the gerographical and oceanographic set-up near RDU appears to skew the winter precip totals because of the baroclinic and coastal fronts that typically set-up because of the land-sea interaction being amplified by the proximity of the Gulf Stream. A strong gradient sets up. That is why Chralotte could get a dusting, while Raleigh is buried, or Rocky Mount experiences catastrophic flooding, while RDU sees moderate rain.

[griteater]

Saw this update from Isotherm on the upcoming pattern - http://www.lightinthestorm.com/

[griteater]

For CLT in Dec. it's always a I-40 N storm. Last year when we had the good setup and the first big winter storm rolled through it was like 34 and rain here in CLT. So even with favorable conditions for December CLT still has a very hard time getting wintry precip in Dec. We did get the Christmas miracle, but it was only so special because it happened for the first time in 44 years which tells you something.

Interestingly enough, of the top 10 snows of all-time at CLT, more have occurred in December (4) than any other month....granted, none of those 4 have occurred post-1930

[Coach B]

Interestingly enough, of the top 10 snows of all-time at CLT, more have occurred in December (4) than any other month....granted, none of those 4 have occurred post-1930

Interesting! Of the top 9 snows in Nashville three of them occurred in the second half of March and only one was in January.

http://www.srh.noaa.gov/ohx/?n=snowstorms

[Mr Bob]

I think this thread should be locked until there is some sign at all that the pattern will change.

[kanc2001]

Read my post again. Did you read it all?

Edit: comparing ATL to Nashville and Charlotte is not fair since they are a good bit further north.

but even Columbia, SC has had more 6"+ snows recently than ATL

[CaryWx]

I think this thread should be locked until there is some sign at all that the pattern will change.

Quit trying to show-off for Widre.

[Brick Tamland]

Quit trying to show-off for Widre.

I think Widre is so bored with the current pattern that he feels it's not even worth the energy to come here and be snarky.

[GaStorm]

Latest from Larry Cosgrove. Sorry if already posted. This is not the first I've read about a possible upcoming SSW event that could force the polar vortex south/turn the AO negative. It's my understanding that the cold outbreak in NA when/if the AO finally turns negative could be historic due to the incredible build up of cold air in the North Pole during the recent historic positive phase of the AO.

DT also posted on this. "SSW significant stratospheric warming event... possible precursor to major pattern change. 0Z EURO and GFS 11-15 day ensemble REALLY showing MAJOR SSW event over western Canada pushing towards Canadian side of arctic circle"

[BullCityWx]

I think you should be locked from posting. No one's forcing you to look at it. If someone changed it to "Long Range Forecast", would it really make you that much happier? Sorry, but your posts on this thread have been annoyingly negative and pointless. There has been a lot of solid discussion about a proposed patter change/lack thereof and the reasoning behind each line of thought.

Exactly what has been pointless about my posts? I've had a point in every single one of them. I'm using cold, hard facts to back up my arguement. There is just no need for this thread to be around(which originally was about a LR run of the GFS).

[Cold Rain]

Exactly what has been pointless about my posts? I've had a point in every single one of them. I'm using cold, hard facts to back up my arguement. There is just no need for this thread to be around(which originally was about a LR run of the GFS).

Maybe if you keep saying it over and over and over, it'll get to the 50 page limit sooner and be locked by default.

[beanskip]

Yet another day of afternoon LR model runs has come and gone and still no pattern change in site. Euro has a nice cutoff low over the southern plains at Day 10, but the SE ridge is entrenched and that low will have no choice but to head NE toward the Great Lakes or be an Apps runner at best.

No signs of -NAO or -AO.