Winter 2013-14 Pattern Discussion III

[sparkync]

That's some intense cold for late February. Maybe we'll have one more shot at a solid storm before winter ends.

in this pattern it wouldn't surprise me

[CarlHill]

Well, the 850 temps are there at the moment and the 1000-700 thickness looks good, we need more, however...

[CarlHill]

Sometimes I wonder why we dick around with this stuff so far out, but I think the supressed optimist in us just want to come out!

[Iceagewhereartthou]

That's some intense cold for late February. Maybe we'll have one more shot at a solid storm before winter ends.

6-8 degrees below late Feb average would be intense cold? Isn't this graph departure from 30 year norm? Sounds more like a gentle cool front.

[jacobr57]

6-8 degrees below late Feb average would be intense cold? Isn't this graph departure from 30 year norm? Sounds more like a gentle cool front.

7 degrees celsius below average? Seems intense to me. Not to mention its closer to 10 in many areas.

[Jon]

6-8 degrees below late Feb average would be intense cold? Isn't this graph departure from 30 year norm? Sounds more like a gentle cool front.

7 degrees celsius below average? Seems intense to me. Not to mention its closer to 10 in many areas.

 

The scale is in C so you have to convert to a Fahrenheit scale...so it's (9/5) of that scale...

-1 (9/5) = -1.8

-2 = -3.6

-4 = -7.2

-6 = -10.8

-10 = -18

 

So the ensemble mean is -10 to -18 or so below average across the SE.

 

There's also a few things to keep in mind here...

1) It's an ensemble map so there are extremes both in the positive and negative territory. For example, one 2m temp anomaly member is around -16 (*C) 2mT anomaly or more all in the SE all the way down to Miami. That would be single digit lows, but that's the extreme.

2) It's a 2mT ensemble map. It's better to look at 500mb anomaly maps to detect trends as if you take a look at 500mb the hour these 2m temps were taken from the trough is ugly and if it's going to happen the way the Euro says, it's not going to look like that...so I'd expect the temps to be colder.

 

Verbatim, we're looking at 20-25 degree low in Raleigh instead of a 39 degree low, based off the maps posted above. IF the trough happens as depicted on the Euro control or something like that, it could go low teens I suspect, but it's too far out to dabble in 2m temps, try to sniff out the overall pattern first and see how far the PV dips into SE Canada/Lakes/Hudson Bay.

 

Either way, this is a strong signal for a trough setting up on the east coast and you should expect mean temperatures for this time period to trend colder (-10+) as we get closer if it's really honing in on a deep trough setting up on the east coast.

[Iceagewhereartthou]

The scale is in C so you have to convert to a Fahrenheit scale...so it's (9/5) of that scale...

-1 (9/5) = -1.8

-2 = -3.6

-4 = -7.2

-6 = -10.8

-10 = -18

 

So the ensemble mean is -10 to -18 or so below average across the SE.

 

There's also a few things to keep in mind here...

1) It's an ensemble map so there are extremes both in the positive and negative territory. For example, one 2m temp anomaly member is around -16 (*C) 2mT anomaly or more all in the SE all the way down to Miami. That would be single digit lows, but that's the extreme.

2) It's a 2mT ensemble map. It's better to look at 500mb anomaly maps to detect trends as if you take a look at 500mb the hour these 2m temps were taken from the trough is ugly and if it's going to happen the way the Euro says, it's not going to look like that...so I'd expect the temps to be colder.

 

Verbatim, we're looking at 20-25 degree low in Raleigh instead of a 39 degree low, based off the maps posted above. IF the trough happens as depicted on the Euro control or something like that, it could go low teens I suspect, but it's too far out to dabble in 2m temps, try to sniff out the overall pattern first and see how far the PV dips into SE Canada/Lakes/Hudson Bay.

 

Either way, this is a strong signal for a trough setting up on the east coast and you should expect mean temperatures for this time period to trend colder (-10+) as we get closer if it's really honing in on a deep trough setting up on the east coast.

Good info. Your numbers just illustrate my point though. Obviously this map is just for fun at this point, but verbatim, most of the SE fits into the 6-8 below range, which would put most people in the mid to upper 20s. I would not call that intense cold for late Feb or early March for that matter, unless your talking about deep gulf coast south (and certainly not comparable to the Jan cold snaps which had temps 25-30 degree F below normal). With the next 10 days being above average, it is going to be difficult for non-mountain peeps to have much of a shot left at winter weather as the weather really starts to head towards spring in late Feb most years. Even if there is a quick shot of relatively cold air it will take perfect timing (which it does outside mtns regardless of month anyway) to get anymore fun stuff. Here's hoping!   

[superjames1992]

March snows are hardly unusual... I think MBY averages 1.7" per March and that's pretty impressive and comparable to February when you consider that the vast majority of that comes in the first couple weeks of the month.

I never understand why people write off March.

[Iceagewhereartthou]

Well I don't write it off, it's just that for each day you get further into March, it is harder and harder to get something (something that isn't true from say, Mid Dec to Mid Feb). Yeah we have had some good snows in March, even in the upstate, but they are few and far between. I guess I am speaking from an IMBY perspective, but I am still hoping to see a good snow, and having to rely on end of Feb or March leaves me with a very low probability. Can it happen- yes. But hey, I could also win the lottery.   

[Jonesing for a chase]

Euro showing interesting solution again starting days 8/9 after our little warm up.  This winter has not been dull.

[Tacoma]

Euro showing interesting solution again starting days 8/9 after our little warm up.  This winter has not been dull.

kinda waiting for the more experienced folks to start reading the models.  hope its another nice snowstorm.  Euro had this last storm pegged 10 days out. 

[Jon]

00z Euro with a pretty good snow RDU and west 2/24-2/25 and the 00z GFS also has this storm...however, the 00z Euro EPS mean is inland. 00z Canadian has the storm also however it also has a 994mb low over the lakes that ruins our system for us, you want that to be non-existent or we need this storm to slow down. 06z GFS doesn't have it and only has rain because of this system.

 

All it would take is this system to slow down a bit and most of us will be in game as the 850's move in quick, and unlike the other storm we'll have a cold air source to tap throughout the system. Something to watch lets just hope it trends later and the Euro ensembles pick it up.

[mackerel_sky]

00z Euro with a pretty good snow RDU and west 2/24-2/25 and the 00z GFS also has this storm...however, the 00z Euro EPS mean is inland. 00z Canadian has the storm also however it also has a 994mb low over the lakes that ruins our system for us, you want that to be non-existent or we need this storm to slow down. 06z GFS doesn't have it and only has rain because of this system.

All it would take is this system to slow down a bit and most of us will be in game as the 850's move in quick, and unlike the other storm we'll have a cold air source to tap throughout the system. Something to watch lets just hope it trends later and the Euro ensembles pick it up.

Our last storm also had the Great Lakes low on alot of the 7-10 out runs , only to not actually be there at storm time. The big thing is most models are showing a storm in this timeframe and cold nearby, that's good ten days out

[Cheeznado]

I think we will have one more cold shot, all of the models and ensembles are showing that after our brief torch/rainy pattern the western ridge amplifies again, that seems to be a given. The Euro weeklies are interesting in that they suggest a possible AK block which would allow a breakthrough of the southern branch after the cold settles in here. A log way to go and climo would say that having 3 significant winter events in Atlanta in one season is maybe unprecedented, but who knows in this crazy winter. For now will enjoy the warmup and maybe some thunder later in the week.

[HKY_WX]

i think we have a solid month left of possible winter weather. mainly b/c the considerable pna ridging that continues to show up on the models and the persistent arctic shot's we've had since early january. wouldn't take to much for a storm to pop up. the pattern has been much more favorable for snow since the start of february. don't see any reason it won't continue.

[GaWx]

Folks,

 The 12Z Euro, due to a 1050 mb Arctic high that reaches ND on 2/25 and then plunges down to the southern Plains 2/26 at a still strong 1047 mb, has verbatim what would be a record low high at KATL on 2/26 and at other locations and would seemingly challenge record lows of 2/27 with 850's down to a frigid -15 C at KATL/KRDU!! It also has a very strong western ridge then, which implies more cold likely after this airmass.

 

 Although the Euro is likely imo overdoing the cold somewhat (I'm guessing the high wouldn't still be 1047 mb in the southern Plains), this is still more evidence that sig. cold is far from over and that there won't be an early spring in the SE US. Bring it on!

[GaWx]

I think we will have one more cold shot, all of the models and ensembles are showing that after our brief torch/rainy pattern the western ridge amplifies again, that seems to be a given. The Euro weeklies are interesting in that they suggest a possible AK block which would allow a breakthrough of the southern branch after the cold settles in here. A log way to go and climo would say that having 3 significant winter events in Atlanta in one season is maybe unprecedented, but who knows in this crazy winter. For now will enjoy the warmup and maybe some thunder later in the week.

 

ATL actually has had about eight seasons since the late 1800's with what I'd consider three or more significant events (so, about one every 17 years):

 

- 2010-11: sig. SN Dec., Major SN/IP/ZR (mainly SN) Jan.; sig. SN Feb.

- March, 1960, alone, had three sig. to major events including a major snow and a major ZR

-1935-6 had four significant wintry events in ATL between late Dec. and early Feb., three of which were MAJOR events (2 major ZR's and a whopping 8" snow).

- 1917-8 likely had three to five sig. events: two major events in Dec.-Jan. (one IP/SN and one ZR) and also had three other wintry events in Jan. from, liquid equivalents between 0.10" and 0.15", each, any of which could possibly be considered significant depending on criteria

- 1911-12 had four significant events between Jan and Feb, including one major ZR and three sig. snows of 1-3".

- 1903-04 may have had as many as three sig. events. There definitely were one major Jan snow and one sig. Dec. snow and likely a sig. ZR in Feb.

- 1894-5: three sig. events: 2 major SN in Feb. and one sig. snow Dec. Total Feb. snowfall: 11.6"!

- 1884-5: at least three sig. events: sig. ZR Dec., major ZR/IP Jan., and series of snows Feb. over four days that added up to major amounts near 7"

[Snowless in Carrollton]

March snows are hardly unusual... I think MBY averages 1.7" per March and that's pretty impressive and comparable to February when you consider that the vast majority of that comes in the first couple weeks of the month.

I never understand why people write off March.

People write off March because the ground temps are warmer, the sun angle higher, temps are usually more marginal than they are in January. And I've personally seen 4 hours of moderate to heavy snow in the middle of the day that amounted to 1/2". Even had hours of thunder snow but because of the warm ground and it being middle of the day it didn't stick.

[Snowless in Carrollton]

Good info. Your numbers just illustrate my point though. Obviously this map is just for fun at this point, but verbatim, most of the SE fits into the 6-8 below range, which would put most people in the mid to upper 20s. I would not call that intense cold for late Feb or early March for that matter, unless your talking about deep gulf coast south (and certainly not comparable to the Jan cold snaps which had temps 25-30 degree F below normal). With the next 10 days being above average, it is going to be difficult for non-mountain peeps to have much of a shot left at winter weather as the weather really starts to head towards spring in late Feb most years. Even if there is a quick shot of relatively cold air it will take perfect timing (which it does outside mtns regardless of month anyway) to get anymore fun stuff. Here's hoping!

I would say 20s is pretty cold considering the average low in Atlanta in late February is 40 !

[GaWx]

People write off March because the ground temps are warmer, the sun angle higher, temps are usually more marginal than they are in January. And I've personally seen 4 hours of moderate to heavy snow in the middle of the day that amounted to 1/2".

 

March, 1960, among others is laughing very hard at these people who write March off for ATL. In addition, these March's are laughing:

 

1924 (4" snow), 1942 (3.7" snow), 1948 (major ZR), 1971 (major ZR), 1980 (2.7" snow), 1983 (7.9" snow), 1987 (1.2" snow), 1993 (Storm of Century with ~7-12" northside and more further north), 2009 (4.2" snow), 2010 (1.1" of snow)

 

Edit: the 12Z Euro ensemble mean supports the late Feb. cold as well as vague hints of a ZR threat near 3/1 fwiw.

 

Edit #2: Forget March for now as the last 4-5 days of Feb. are by no means in the clear at this point.

[franklin NCwx]

Euro ensemble mean has a low coming out of the gulf at 192 hours with a big arctic high in yhe Dakotas!

[mackerel_sky]

March, 1960, among others is laughing very hard at these people who write March off for ATL. In addition, these March's are laughing:

1924 (4" snow), 1942 (3.7" snow), 1948 (major ZR), 1971 (major ZR), 1980 (2.7" snow), 1983 (7.9" snow), 1987 (1.2" snow), 1993 (Storm of Century with ~7-12" northside and more further north), 2009 (4.2" snow), 2010 (1.1" of snow)

Edit: the 12Z Euro ensemble mean supports the late Feb. cold as well as vague hints of a ZR threat near 3/1 fwiw.

Edit #2: Forget March for now as the last 4-5 days of late Feb. are by no means in the clear at this point.

Thanks for the info and historical data! Always fascinating. As has been said , if any winter can produce in late Feb or March, this one could be the one!

[jburns]

People write off March because the ground temps are warmer, the sun angle higher, temps are usually more marginal than they are in January. And I've personally seen 4 hours of moderate to heavy snow in the middle of the day that amounted to 1/2". Even had hours of thunder snow but because of the warm ground and it being middle of the day it didn't stick.

 

Snow rate trumps warm ground and sun angle.  If it snows hard enough, it will accumulate.

[mackerel_sky]

Snow rate trumps warm ground and sun angle. If it snows hard enough, it will accumulate.

Always! Just witnessed it with Tuesday storm. Snowed mod/hvy for hours . Picked up 3-4 inches on grass with air temp at 36 degrees. All accumulating during daylight hours only!

[LithiaWx]

Snow rate trumps warm ground and sun angle.  If it snows hard enough, it will accumulate.

The comment you were responding to is the same person who said they had never seen it snow harder than it did last week

[Tacoma]

Folks,

 The 12Z Euro, due to a 1050 mb Arctic high that reaches ND on 2/25 and then plunges down to the southern Plains 2/26 at a still strong 1047 mb, has verbatim what would be a record low high at KATL on 2/26 and at other locations and would seemingly challenge record lows of 2/27 with 850's down to a frigid -15 C at KATL/KRDU!! It also has a very strong western ridge then, which implies more cold likely after this airmass.

 

 Although the Euro is likely imo overdoing the cold somewhat (I'm guessing the high wouldn't still be 1047 mb in the southern Plains), this is still more evidence that sig. cold is far from over and that there won't be an early spring in the SE US. Bring it on!

isn't there a gulf low about this time showing up in the gulf?

[jburns]

The comment you were responding to is the same person who said they had never seen it snow harder than it did last week

 

Yeah.  It's hard to believe just how hard it can snow until you've experienced it.  That, and the fact that we really could use some education in our reporting of snow rates.  If you're reporting heavy snow for several hours and only have 2" it wasn't heavy snow.

[GaWx]

isn't there a gulf low about this time showing up in the gulf?

 

 There is a weak low on the 12Z Euro but it comes across mainly just before the Arctic air arrives.

[dsaur]

I want the split flow and the cutoff ull to come back....and throw in a 50/50.  You know blocking is about to start up again.  The cycle has taken it away for a good while, and it's about time for the worm to turn.   That way we can get 3 or 4 events within a 3 week period, lol.  After 1960 I thought that would be the norm.  Somehow things didn't work out.  The 60's ended up being cold...but a lot of it was dry cold. T

[Snowless in Carrollton]

Snow rate trumps warm ground and sun angle.  If it snows hard enough, it will accumulate.

In March, generally speaking, you need higher snow rates to get the snow to accumulate than you would in January or early February. Light to Moderate snow just won't cut it in March during the day especially.