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Mid to Long Range Discussion ~ 2023


buckeyefan1
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2 minutes ago, GaWx said:

Yeah, like 1899 that 12Z GFS fantasy winter storm was all the way down to (and past) Phil @pcbjr in Hogtown/Gainesville with ~1/4" of ZR. Unlike 1899, this fantasy is from a series of lows and a large portion of the heaviest SE US qpf is actually ZR with some sleet. The precip in N FL, and SE GA/SC/NC is nearly 100% ZR/IP with the 850 mb 0C line to the NW. It would be a massive/historic icestorm for much of that area but fortunately it isn't real.

Gone on 18z.  Winter is over . 26 inches to severe on 1 run. Useless model 

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18 minutes ago, Grayman said:

Gone on 18z.  Winter is over . 26 inches to severe on 1 run. Useless model 

 A once in 125 year series of deep SE winter storms that suddenly appears on a GFS run out 12-14 days gone on the next run? I'm absolutely shocked and stunned! ;)

  But it is entertaining to see these fantasies. The extreme inaccuracy of models that far out allows for crazy fantasies to appear every once in a while.

  Based on the timing of the upcoming SSW and considering ensembles, I'm expecting this period and a bit beyond to be dominated by near to warmer than normal. The start of a cold dominated pattern related to the SSW would probably not be before ~Feb 10th at the earliest based on analogs (shown on maps I posted yesterday). Around then winter will most likely be restarting! Far from over imo!

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12 minutes ago, GaWx said:

 A once in 125 year series of deep SE winter storms that suddenly appears on a GFS run out 12-14 days gone on the next run? I'm absolutely shocked and stunned! ;)

  But it is entertaining to see these fantasies. The extreme inaccuracy of models that far out allows for crazy fantasies to appear every once in a while.

  Based on the timing of the upcoming SSW and considering ensembles, I'm expecting this period and a bit beyond to be dominated by near to warmer than normal. The start of a cold dominated pattern related to the SSW would probably not be before ~Feb 10th at the earliest based on analogs (shown on maps I posted yesterday). Around then winter will most likely be restarting! Far from over imo!

Dang, your facts getting in the way of my weenie emotions lol. Hope your right. Thanks for all the info you post. We need to have a contest on here to spice things up while we wait .

 

biggest weenie

most negative

most informative 

 

 

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1 hour ago, Upstate Tiger said:

The 18z came back to reality but the same features are still there including the weakening of the SER.  Wouldn’t totally laugh off the time frame.  Heck, it’s Jan 21 and Clemson’s in first place in the ACC. If hell can freeze over, anything’s possible. :weenie::P

And Brown L is closing out close games. Something’s bound to give

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2 hours ago, eyewall said:

The clock is running and we may get a pattern shift just in time for rain and 40s in March lol.

I'd say we're already in the midst of a pattern shift from torch dominating most of the month to averaging near normal (some BN and some AN) for the rest of this month and possibly further in the SE and in much of the E US. Ironically, the 12Z EPS is significantly colder overall vs prior runs in the SE (coldest run in quite awhile) in the 11-15 day. The last couple have been colder than prior runs. Also, the 12Z GEFS is as cold as any of the last few days. Neither ensemble now has it mild in early Feb. with near to a little BN on the 12Z EPS/GEFS in most of the SE. The colder model trend could be a psyche/wrong, of course, especially with them being too cold overall this winter to date, but regardless, I didn't see a model cooling trend coming. 

 12Z EPS mean of 51 members is a whopping 10 F or so colder in not only the SE US but also almost the entire E 1/3 of the US vs just three runs ago in much of the 11-15! Example: the ensemble mean at Charlotte for 12Z on 2/4 was an AN 40 just three runs ago and is now a BN 30!

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 Tomorrow will be when the SSW starts in the Arctic. This has been the timing on the GEFS since I started following it closely a week ago. It still looks about as strong as it ever has on the GEFS. The N Pole is still progged to warm at 10 mb a whopping 40C/72F+ during just a 5 day period ending 1/28! And then it warms even more into early Feb.

 What's still in doubt is whether it gets classified as a "major" SSW or a "minor" SSW. "Major" requires a wind shift from W to E at the 10 mb level at 60N. Regardless, it will be a strong SSW (rapid, strong warming). The eventual effects on the SE remain to be seen. However, the history of actual "major" SSW events suggests that the bulk of potential significant, persistent cooling in the SE US related to this would most likely not occur til at least 10-15 days after the SSW (per the maps I posted two days ago) when a -AO dominates. These same maps as well as stats I looked at suggest that the 1-2 week period right after the SSW would typically average near to AN prior to the cold with a +AO prevailing.

 Looking at the MJO forecasts, the GEFS is still largely on its own with a forecast of a moderate phase 4 within two weeks. The others turn back into the COD, which wouldn't be a warm signal.

 We'll see how this evolves, especially since it may not reach the "major" SSW classification. But would that matter much with this strong of a warming? We'll see.

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1 hour ago, GaWx said:

 Tomorrow will be when the SSW starts in the Arctic. This has been the timing on the GEFS since I started following it closely a week ago. It still looks about as strong as it ever has on the GEFS. The N Pole is still progged to warm at 10 mb a whopping 40C/72F+ during just a 5 day period ending 1/28! And then it warms even more into early Feb.

 What's still in doubt is whether it gets classified as a "major" SSW or a "minor" SSW. "Major" requires a wind shift from W to E at the 10 mb level at 60N+. Regardless, it will be a strong SSW (rapid, strong warming). The eventual effects on the SE remain to be seen. However, the history of actual "major" SSW events suggests that the bulk of potential significant, persistent cooling in the SE US related to this would most likely not occur til at least 10-15 days after the SSW (per the maps I posted two days ago) when a -AO dominates. These same maps as well as stats I looked at suggest that the 1-2 week period right after the SSW would typically average near to AN prior to the cold with a +AO prevailing.

 Looking at the MJO forecasts, the GEFS is still largely on its own with a forecast of a moderate phase 4 within two weeks. The others turn back into the COD, which wouldn't be a warm signal.

 We'll see how this evolves, especially since it may not reach the "major" SSW classification. But would that matter much with this strong of a warming? We'll see.

 

GaWx,

Do you know when we would expect to see the wind shift/reversal if it does actually occur? 

As always, great synthesis on the upcoming forecast

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3 hours ago, CaryWx said:

 

GaWx,

Do you know when we would expect to see the wind shift/reversal if it does actually occur? 

As always, great synthesis on the upcoming forecast

Thanks. If it occurs, I think it would be near or just after the end of the rapid 10 mb Arctic warming or, say, ~1/28 or a little later. The 60N winds will drop drastically per models from their pre SSW near 50 m/s to under 15. If they would get to below 0, that would be considered a reversal as I understand it. But what if it were to stop at, say, 10? That would be 80% of the way to 0. Would that be close enough effectwise to result in similar changes to what an actual "major" typically causes?? 
 
 The N Pole is progged to warm up at 10 mb from near -75 C to ~-35 C on 1/28. Normal/average for that date is ~-55 to -60 C. But then it is progged to warm further to -20 C on 2/2, which would be 35 C AN  for the date and 10 C AN for mid summer high normals!

*Edited for corrections

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7 hours ago, GaWx said:

I'd say we're already in the midst of a pattern shift from torch dominating most of the month to averaging near normal (some BN and some AN) for the rest of this month and possibly further in the SE and in much of the E US. Ironically, the 12Z EPS is significantly colder overall vs prior runs in the SE (coldest run in quite awhile) in the 11-15 day. The last couple have been colder than prior runs. Also, the 12Z GEFS is as cold as any of the last few days. Neither ensemble now has it mild in early Feb. with near to a little BN on the 12Z EPS/GEFS in most of the SE. The colder model trend could be a psyche/wrong, of course, especially with them being too cold overall this winter to date, but regardless, I didn't see a model cooling trend coming. 

 12Z EPS mean of 51 members is a whopping 10 F or so colder in not only the SE US but also almost the entire E 1/3 of the US vs just three runs ago in much of the 11-15! Example: the ensemble mean at Charlotte for 12Z on 2/4 was an AN 40 just three runs ago and is now a BN 30!

There has been a signal for the first week of Feb for a while.  What does climo say for that period, Mr. Abacus? Going from 8.4 in Dec to 70's in Jan, has me expecting something equally as anomalous soon....like 100 year sleet storm, lol.

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4 hours ago, dsaur said:

There has been a signal for the first week of Feb for a while.  What does climo say for that period, Mr. Abacus? Going from 8.4 in Dec to 70's in Jan, has me expecting something equally as anomalous soon....like 100 year sleet storm, lol.

 Well Tony, don't shoot the abacus lol. In the first week of Feb for whatever reason, I could find no major snow or sleet officially at Atlanta! I found nonmajor ones, of course, and several bad icestorms. And I'm sure you know there have been a good # of major snows/sleets both the week before and the week after. (Peak at Atlanta is near mid-Feb.) One of these days that will change for the first week of Feb. Maybe that's what you're alluding to for this year as that would be highly anomalous!

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3 hours ago, GaWx said:

 Well Tony, don't shoot the abacus lol. In the first week of Feb for whatever reason, I could find no major snow or sleet officially at Atlanta! I found nonmajor ones, of course, and several bad icestorms. And I'm sure you know there have been a good # of major snows/sleets both the week before and the week after. (Peak at Atlanta is near mid-Feb.) One of these days that will change for the first week of Feb. Maybe that's what you're alluding to for this year as that would be highly anomalous!

Thanks, Larry.  I thought I remembered late Jan, then mid Feb as being more propitious times.  I guess it's Goofy being goofy trying to put a major on at the wrong time.  One of these days, though, it will be in the 20's in Cuba, and I'll get my foot of sleet....just hope I'm not experiencing it from under the ground.

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 The 6Z GEFS mean is the coldest GEFS mean yet for Feb 3-5 in the SE (mainly MB) though the 0Z EPS isn't as cold as yesterday's 12Z, which was the coldest EPS so far. The 6Z GEFS is actually colder than yesterday's 12Z EPS.

 Edit: The mean Arctic surface high track on the 6Z GEFS during that potentially very cold period is through the Ohio Valley to the NE US, which is pretty close to the optimal track for potential widespread SE wintry precip though that doesn't at all mean it would likely occur as I don't think many members actually have widespread wintry precip.

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Peep the CPC MJO discussion for why the RMM plots are biased too weak in the extended. This discussion updates Monday afternoons. If that holds true, guidance showing a -PNA in early to mid-Feb will hold true.

As for next week, here's a cluster analysis on the 8-to-10-day period. Think of the 4 top solutions as ensembles that are grouped together based on their similarity. No cluster is necessarily more likely than the other, but you can see the percentages of each ensemble that supports that mean. C - Canadian, G - GEFS, E - EPS. The full ensemble mean and anomalies are on the very bottom, so it's a good way to look at all the ensembles blended together. There are important differences in the Pacific, but you'll note that even with the blocking on some guidance over AK (cluster 3), all the cold air dumps into the West, Plains and Great Lakes during this period. If the Hudson Bay vortex ends up being two separate areas as is hinted at, that could open the door for more cold air damming to sneak in east of the mountains.

2023012300_3_day_average_cluster_hgt_500_forecasts_k_means_conus.thumb.png.6cdc6e89f97cab619a5515a7bfe61c7e.png

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19 minutes ago, purduewx80 said:

Peep the CPC MJO discussion for why the RMM plots are biased too weak in the extended. This discussion updates Monday afternoons. If that holds true, guidance showing a -PNA in early to mid-Feb will hold true.

As for next week, here's a cluster analysis on the 8-to-10-day period. Think of the 4 top solutions as ensembles that are grouped together based on their similarity. No cluster is necessarily more likely than the other, but you can see the percentages of each ensemble that supports that mean. C - Canadian, G - GEFS, E - EPS. The full ensemble mean and anomalies are on the very bottom, so it's a good way to look at all the ensembles blended together. There are important differences in the Pacific, but you'll note that even with the blocking on some guidance over AK (cluster 3), all the cold air dumps into the West, Plains and Great Lakes during this period. If the Hudson Bay vortex ends up being two separate areas as is hinted at, that could open the door for more cold air damming to sneak in east of the mountains.

2023012300_3_day_average_cluster_hgt_500_forecasts_k_means_conus.thumb.png.6cdc6e89f97cab619a5515a7bfe61c7e.png

So if I'm reading this correctly cluster-1 with the highest percentage supports this statement below?  Cluster-4 has it too but not so much for the southeast

 "If the Hudson Bay vortex ends up being two separate areas as is hinted at, that could open the door for more cold air damming to sneak in east of the mountains."

Not that it is any more likely as 31% isn't a fantastic chance to start with but decent among 4 cluster possibilities. 

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2 hours ago, CaryWx said:

So if I'm reading this correctly cluster-1 with the highest percentage supports this statement below?  Cluster-4 has it too but not so much for the southeast

 "If the Hudson Bay vortex ends up being two separate areas as is hinted at, that could open the door for more cold air damming to sneak in east of the mountains."

Not that it is any more likely as 31% isn't a fantastic chance to start with but decent among 4 cluster possibilities. 

Yeah, cluster 1 (31%) is sort of the statistical "mode" of the four clusters. However, if ensemble mean bias were to also be taken into account, I think the true chance would be lower than 31% as there's often been too much west coast ridging/E US troughing overall this winter in the 11-15 resulting in a cold bias in the SE/E US. In other words, I think that if model bias were to be incorporated, the bias corrected cluster 1 would be reduced substantially from 31% and some or all of the other three clusters increased.

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 The 12Z GEFS mean has about the most wintry precip over the well inland SE overall (not for my and other coastal/deep SE areas) as any other GEFS run in early Feb. The precip falls anywhere from Feb 2nd through 7th depending on the member/area. That doesn't mean there will necessarily be anything significant or that it is necessarily likely. I'm just saying what the mean has compared to earlier runs. This doesn't say what % of the members have it nor does it take into account model bias this season. But it probably means a slightly increased chance vs earlier for well inland areas of the SE.

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 Yesterday's 12Z EPS mean had been the coldest run yet for the SE in the 11-15. Then today's 0Z backed off some. But now the new 12Z is back to at least as cold as yesterday's 12Z, and even slightly colder at times. For example, yesterday I had noted that the 12Z mean had Charlotte at 30 as of 12Z on 2/4, which was 10 colder than just three runs earlier. Then today's 0Z backed off some to 33. The brand new run has 29. This is significant because this is near the period that some GFS runs/GEFS members are sniffing out a somewhat elevated chance for wintry precip.

 Looking at wintry precip., this new run's mean has a good bit more than yesterday's almost as cold run and this is mainly for inland areas though the NC coast, especially upper, has a bit of a signal.

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