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December Forecast Discussion


Wow

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I hear you and we've seen plenty of those over the years .... BUT, imo, CAD events are like three-point shots -- you tend to remember the makes and forget the misses. If the CAD is right, it overperforms. But plenty of time CAD never materializes or becomes in-situ and never really locks in.

If I only had a dime for every time someone said a storm involving damming was too warm in the day 7-8 range...

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If I only had a dime for every time someone said a storm involving damming was too warm in the day 7-8 range...

Heart of the damming area here...I agree. Highs usually get busted 10 or so degrees. Temps never move that fast, it would take a strong wind or something to knock the fog/clouds away.

Meaningful questions to ponder...

Do we take EURO temps verbatim this far out?

Does it have any warm bias?

Could temps possibly trend cooler over the next 8 days?

Will the GFS or EURO stay consistent without shifting a few hundred miles for 8 days straight?

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Serious question. When was the last true damming situation for the area? I feel like for years the only way to get a significant winter storm was if the storm tracked well south along the gulf coast. There has been a serious absence of these setups. As beanskip said they usually end up as in-situ events that don't produce anything significant.

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Well, there was the infamous Larry Cosgrove event where he pooh poohed the CAD and ended up with a chicken farm's worth of egg on his face. I remember one SuperCAD that was so strong it actually started wrapping back around the mountains toward southern Tenn. I'm getting too old to remember which years those were, though.

Serious question. When was the last true damming situation for the area? I feel like for years the only way to get a significant winter storm was if the storm tracked well south along the gulf coast. There has been a serious absence of these setups. As beanskip said they usually end up as in-situ events that don't produce anything significant.

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There is a big difference between a favorably located High that "appears" be funneling air that is not quite cold enough in a long-term chart and a wedge generated by a High way up in north central Canada.

For anyone wanting significant snow and ice in any part of the central Carolinas or deep into the SE out of this storm, you'd better hope that the position of the depicted High changes in future runs or that it stays in the same spot and strengthens by about 2 dozen mb.

Things can change, obviously. But what is depicted today, if the key features align in reality as shown today, it will be a cold rain for most.

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Serious question. When was the last true damming situation for the area? I feel like for years the only way to get a significant winter storm was if the storm tracked well south along the gulf coast. There has been a serious absence of these setups. As beanskip said they usually end up as in-situ events that don't produce anything significant.

If you're talking about an actual ZR or IP storm, ATL's last four major ZR/IP storms have been as follows:

12/2005, 1/2005, 1/2000, and 1/2000 (yes there were two in 1/2000).

Prior to that, the last major ZR or IP was all of the way back in 1/1988, which made for the longest drought on record for ATL major ZR/IP (12 years). ATL gets a major ZR/IP about once every 4 years on average. So, ATL is a bit due for one fwiw since it has been 7 years. Since 1879, the longest between ATL major ZR/IP's has been the following:

12 years (1988-2000)

11 years (1949-60)

10 years (1892-1902)

10 years (1/1923-12/1932)

9 years (1979-88)

7 years (1885-1892)

7 years (2005-2012)

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Going to get some snow in our mountains first...starting in 84 hours. 1inch marker now even going off with the 18z GFS...and we know higher elevations may see more than that. Won't be going anywhere w/ the cold air Friday...good news for ski resorts....looks like they will have time to make snow before the holidays.

GFS_3_2012121718_F96_SNOWIN_SURFACE.png

NWS Blacksburg

Winds will turn to the northwest behind the front Thursday night. Everybody's friend...light upslope snow...makes yet another appearance over the Greenbrier valley and higher elevations in western VA/NC.

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The trend lately has been a displaced PV(not split)and keeping it in Siberia not getting into Greenland.Better chances for blocking to set up.

Also guidance continues to pour strat warming into Canada at 10-30 hPa down to 100hPa.Some runs are stronger,some weaker but all are doing this.What will be interesting to watch is if the warming can get to the troposphere(surface)and can fight off the -PNA.

Another clue to watch is the zonal wind forecast.ECMWF is strong today with negative winds at 70N up to the pole in days 8-10,strong look for blocking.We actually have a forecasted reversal at about 67N at 10hpa today,if this gets to 60N that's a forecasted SSW.None of this may not be there tomorrow on the guidance but it's there today.

Also just remember where we live,we will probably be the last to the bowl when it comes to seeing the possible affects.

Just my opinion.

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Well, there was the infamous Larry Cosgrove event where he pooh poohed the CAD and ended up with a chicken farm's worth of egg on his face. I remember one SuperCAD that was so strong it actually started wrapping back around the mountains toward southern Tenn. I'm getting too old to remember which years those were, though.

That was awesome! Lookout and several others here took poor ol' Larry to task on that event. He was so adamant that it was going to be a non-event and our resident CAD experts owned his azz.

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***Fwiw***, the new Euro weeklies look pretty chilly and wet for the SE in general with near to above avg. precip. and near to below avg. temp.'s after a warm 12/17-23. So, fwiw, 12/24-1/13 look fairly good if these are to be believed.

Patternwise at 500 mb, the good news is that they have a nearly continuous E Canada/SW Greenland block and a somewhat -AO on avg. The bad news is that the pesky -PNA doesn't seem to go away.

All in all, I liked what I saw. However, the fwiw of the weeklies can't be overemphasized and I would have preferred to see a higher PNA.

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I haven't been referring to it by name, but that's the blocking pattern I've been referring to all along.

Thanks for the discussion you've brought to the table on this storm. Not sure why folks are getting so dramatic about it given it's still December. If this pans out it's a bonus, if not on to Jan. which either way both models seem to feel is going to put us in the game.

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***Fwiw***, the new Euro weeklies look pretty chilly and wet for the SE in general with near to above avg. precip. and near to below avg. temp.'s after a warm 12/17-23. So, fwiw, 12/24-1/13 look fairly good if these are to be believed.

Patternwise at 500 mb, the good news is that they have a nearly continuous E Canada/SW Greenland block and a somewhat -AO on avg. The bad news is that the pesky -PNA doesn't seem to go away.

All in all, I liked what I saw. However, the fwiw of the weeklies can't be overemphasized and I would have preferred to see a higher PNA.

After further analysis, I admittedly like what I see on the new Euro weeklies even a bit more. Here's why:

1) Both the NAO and AO are more negative (stronger blocking) than the Euro weekly run from four days ago, which covered the same exact four weeks.

2) After a slightly warmer week #1 in the E US (no surprise after the warm adjustments of the last few days), the 2 meter temp.'s for the subsequent three weeks in the E 1/2 of the US are overall significantly colder vs. the Euro weekly run from four days ago, which as I mentioned covers the same exact four weeks (through 1/13). Weeks 2 and 4 are much colder than that from the prior run whereas week 3 is a little colder. As a matter of fact, weeks 2-4 actually have colder than normal covering most of the country from coast to coast.

I, of course, do take these with a big grain of salt. However, so that the reader doesn't just think that I'm a nonobjective cynic, I will point out two encouraging things about the weeklies that may mean there's some credibility:

1) This is the coldest week 2-4 run anomalywise at two meters for the US as a whole by a good margin since at least early Sep. (as far as I went back). That covers 31 Euro weekly runs. Actually, I saw no other run having all of weeks 2-4 with such widespread below normal U.S. temp.'s

2) The runs in late Nov. for Dec. were largely warm. The 11/29 run had a torch for four weeks.

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If Oklahoma and Texas can go to 10 inches of snow with 1 change of the GFS run, can we do the same here?

hour 228 18z

Nope. I feel OK and even Texas has a greater chance for snow this winter than NC, just the way it is. I'd believe that solution more than 10" in Raleigh, sadly.

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Nope. I feel OK and even Texas has a greater chance for snow this winter than NC, just the way it is. I'd believe that solution more than 10" in Raleigh, sadly.

That really isn't all that uncommon for that part of TX/OK. So yes, climo speaking I think it is much more likely to happen in the area shown than in eastern NC. TW

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That really isn't all that uncommon for that part of TX/OK. So yes, climo speaking I think it is much more likely to happen in the area shown than in eastern NC. TW

Raleigh is eastern NC? :P Yeah I was making the same point. The "If OK/TX can get snow, can't we" statement doesn't quite work, ever.

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THIS IS A MUST READ: Briarcreek is correct and this is exactly what he has been referncing along with Brandon. If you don't understand REX Blocks and pattern recoginition, you need to take 5 minutes and learn some crucial basic information explained in this post.

Burger the Euro ensembles are very telling and carry alot of weight at the moment, more so than the euro operational.

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Nope. I feel OK and even Texas has a greater chance for snow this winter than NC, just the way it is. I'd believe that solution more than 10" in Raleigh, sadly.

I guess I was trying to say or point out how the GFS came out of nowhere to give them 10 or so inches...the other runs were nowhere near as pronounced. Can we see that ripple effect down the road here in the runs to come? idk...but I agree w/ OK and TX having a greater chance of snow than say Raleigh.

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THIS IS A MUST READ: Briarcreek is correct and this is exactly what he has been referncing along with Brandon. If you don't understand REX Blocks and pattern recoginition, you need to take 5 minutes and learn some crucial basic information explained in this post.

Burger the Euro ensembles are very telling and carry alot of weight at the moment, more so than the euro operational.

Yep and the Euro ENS said it's a go. We'll wait and see but I'm excited...not sure why some are so intense about this not having any chance or being anything like last year.

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***Fwiw***, the new Euro weeklies look pretty chilly and wet for the SE in general with near to above avg. precip. and near to below avg. temp.'s after a warm 12/17-23. So, fwiw, 12/24-1/13 look fairly good if these are to be believed.

Patternwise at 500 mb, the good news is that they have a nearly continuous E Canada/SW Greenland block and a somewhat -AO on avg. The bad news is that the pesky -PNA doesn't seem to go away.

All in all, I liked what I saw. However, the fwiw of the weeklies can't be overemphasized and I would have preferred to see a higher PNA.

I will take what the Euro weeklies are showing :D Any moisture we can get around here is a good thing. I'm tired of seeing this area in various shades of red and orange :lol: btw.....a higher PNA would be nice ;)

I haven't been referring to it by name, but that's the blocking pattern I've been referring to all along.

I've been enjoying reading your summaries and glad to see you are posting more :hug:

Thanks for the discussion you've brought to the table on this storm. Not sure why folks are getting so dramatic about it given it's still December. If this pans out it's a bonus, if not on to Jan. which either way both models seem to feel is going to put us in the game.

:lol: This is so very true. It happens every year, but it seems after last years disappointment it has magnified. We live in the south and shouldn't expect to see anything frozen with every system. On average there are only a couple of actual chances we have every year and the winter solstice hasn't even begun yet :lol:

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