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Mid to Long Range Discussion ~ 2024


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 The 0Z EPS, which is colder than the GEFS, is the coldest run yet overall for midmonth (1/14+) for the C & E US, including 5-10 BN SE. This includes extreme cold anomalies over the C Plains and a very cold Midwest. It implies two Arctic highs coming down into the Plains feeding cold but not plunging into the SE. This of course doesn’t necessarily mean there would be a widespread significant SE winter storm near or just after this cold period (1/14-21+) as widespread big SE winter storms are pretty infrequent. I’m not even saying I’d bet on it. But if there actually would be a 10+ day period averaging 5-10 BN in the SE during mid to late Jan (at/near the coldest climo means of the year) in El Niño, that would imply an above climo chance for SE wintry precip overall, including a significant winter storm chance. What would be best for snow would be for a very cold high to plunge into the Midwest and then move E near the Ohio Valley instead of into TX/OK because it would allow for the chance for moisture to return while it is still cold.

 Looking at indices, whereas the progged strong right side MJO isn’t at all favorable, the -NAO/-AO keeps the door open. If I get time, I’ll check to see if I can find a big SE winter storm when the MJO was strong on the right.

 Is the EPS right or is it too cold? I don’t know the answer.

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1 minute ago, Leesville Wx Hawk said:

We have a real window of opportunity coming so I hope that we cash in before the pattern relaxes.  GFS operational has been showing some long range digital winter weather.

Honestly in my opinion we are in a relaxation currently. We've really not got into the meat and potatoes of a favorable pattern. Hell it's only January 6th. We've got a lot of time to see this play out. For most of yall one storm is all yall need. 

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2 minutes ago, olafminesaw said:

us_model-en_modusa_2024010612_91_480_399.png

us_model-en_modusa_2024010612_82_480_377.png

These are often overdone but 30-40 mph seems reasonable. RAH is thinking a potential gravity wave event may occur which would briefly induce higher winds.

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image.thumb.png.8e4fbdb979a954443f747ec365e63e9c.png

Note: this is likely overdone but gusts to 40 outside thunderstorms are likely. NWS Raleigh also mentions the possibility of a gravity wave event which could locally enhance winds for a short time.

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7 minutes ago, eyewall said:

These are often overdone but 30-40 mph seems reasonable. RAH is thinking a potential gravity wave event may occur which would briefly induce higher winds.

Right now the highest winds are timed with the slug of moisture. This would elevate the threat beyond what we normally would get from baraclonic winds, along with a small amount of instability. 925mb sustained winds are 65-75 mph around that same frame so some of that would be brought down by any convection. Maybe it could gust to 50 especially East of the Triad.

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3 minutes ago, eyewall said:

image.thumb.png.8e4fbdb979a954443f747ec365e63e9c.png

Note: this is likely overdone but gusts to 40 outside thunderstorms are likely. NWS Raleigh also mentions the possibility of a gravity wave event which could locally enhance winds for a short time.

Is a gravity wave event going to occur in the rear exit of the jet streak? It's looking pretty potent.

gfs_uv250_us_16.png

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2 minutes ago, olafminesaw said:

Is a gravity wave event going to occur in the rear exit of the jet streak? It's looking pretty potent.

gfs_uv250_us_16.png

Hard to say exactly where it will setup but they did say the mountains actually have a higher risk of it as well.

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2 hours ago, GaWx said:

 The 0Z EPS, which is colder than the GEFS, is the coldest run yet overall for midmonth (1/14+) for the C & E US, including 5-10 BN SE. This includes extreme cold anomalies over the C Plains and a very cold Midwest. It implies two Arctic highs coming down into the Plains feeding cold but not plunging into the SE. This of course doesn’t necessarily mean there would be a widespread significant SE winter storm near or just after this cold period (1/14-21+) as widespread big SE winter storms are pretty infrequent. I’m not even saying I’d bet on it. But if there actually would be a 10+ day period averaging 5-10 BN in the SE during mid to late Jan (at/near the coldest climo means of the year) in El Niño, that would imply an above climo chance for SE wintry precip overall, including a significant winter storm chance. What would be best for snow would be for a very cold high to plunge into the Midwest and then move E near the Ohio Valley instead of into TX/OK because it would allow for the chance for moisture to return while it is still cold.

 Looking at indices, whereas the progged strong right side MJO isn’t at all favorable, the -NAO/-AO keeps the door open. If I get time, I’ll check to see if I can find a big SE winter storm when the MJO was strong on the right.

 Is the EPS right or is it too cold? I don’t know the answer.

Followup on my search for a big SE winter storm when MJO was strong on the right:

 Couldn’t find any when right side strong like GEFS has (amp 2+) but found 3 big and 2 moderate storms when MJO was right side moderate (like EPS has):

-1/24/1991: mod SN ATL-CLT; mod phase 4

-3/13/1993: historic SN for many; mod phase 4

-12/18/1996: mod SN ATL-GSP; mod phase 5

-1/9-10/2011: big storm for many; mod phase 5-6

-1/17/2018: big storm for many; mod phase 4

 So, the progged MJO is a negative factor as most of us already knew. However, if it would end up moderate like the EPS instead of the GEFS’ strong, history says that there’d be a shot at a moderate to big winter storm over a good portion of the SE should the SE get as cold as the EPS shows (5-10 BN averaged over up to 10 days). Note that 3 of the 5 were during 1/9-24, in/near the progged cold period and near coldest climo though none were during El Niño.

 How was NAO/AO/PNA/EPO during these 5?

1. NAO range was -0.3 to +1.3.

2. AO range was wide: -3.4 to +2.2 (3 +, 2 -)

3. PNA range VERY narrow: -0.2 to -0.4

4. EPO range -320 to +60 with 4 of 5 strong -

 
So, weak -PNA and strong -EPO prevailed.  None had a moderate or stronger -NAO. AO all over the place.

 Has anyone seen an EPO prog?

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2 hours ago, GaWx said:

Followup on my search for a big SE winter storm when MJO was strong on the right:

 Couldn’t find any when right side strong like GEFS has (amp 2+) but found 3 big and 2 moderate storms when MJO was right side moderate (like EPS has):

-1/24/1991: mod SN ATL-CLT; mod phase 4

-3/13/1993: historic SN for many; mod phase 4

-12/18/1996: mod SN ATL-GSP; mod phase 5

-1/9-10/2011: big storm for many; mod phase 5-6

-1/17/2018: big storm for many; mod phase 4

 So, the progged MJO is a negative factor as most of us already knew. However, if it would end up moderate like the EPS instead of the GEFS’ strong, history says that there’d be a shot at a moderate to big winter storm over a good portion of the SE should the SE get as cold as the EPS shows (5-10 BN averaged over up to 10 days). Note that 3 of the 5 were during 1/9-24, in/near the progged cold period and near coldest climo though none were during El Niño.

 How was NAO/AO/PNA/EPO during these 5?

1. NAO range was -0.3 to +1.3.

2. AO range was wide: -3.4 to +2.2 (3 +, 2 -)

3. PNA range VERY narrow: -0.2 to -0.4

4. EPO range -320 to +60 with 4 of 5 strong -

 
So, weak -PNA and strong -EPO prevailed.  None had a moderate or stronger -NAO. AO all over the place.

 Has anyone seen an EPO prog?

Last I saw was this from the Euro weeklies a couple days ago. IMG_0847.jpeg.be1052351f364fd26abc3935f0250ddd.jpeg

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9 hours ago, SnowDawg said:

Last I saw was this from the Euro weeklies a couple days ago. IMG_0847.jpeg.be1052351f364fd26abc3935f0250ddd.jpeg

 So, the 0Z 1/4 EPS was forecasting a strong -EPO for mid Jan, the period I’m analyzing for SE winter storm chances. That would be a pretty big deal if it verifies. 80% of the moderate right side MJO with widespread SE mod to heavy wintry precip had a strong -EPO.

 This shows an 8 straight day period of sub -150. How often does that occur in any one winter? There have been 40 instances since 1948 or about one every other winter on average. No winter has had more than two. So, if that EPS is right, it would be a pretty big deal, especially when combined with a -AO. But this is all looking to go against a robust MC MJO.
 

 The lengthy strong EPO strings fully in Jan were (temps/wintry precip are for SE):

1/10-18/1957: cold (-PNA, +AO, neut NAO)

1/18-29/1961: very cold/wintry (+PNA, -AO, neut NAO)

1/15-22/1962: cold/wintry (-PNA, +AO, neut NAO)

1/9-31/1963: very cold (+PNA, -AO, -NAO)

1/17-26/1969*: slightly AN (-PNA, -AO, -NAO)

1/1-11/1974: mild (-PNA, +AO, neut NAO)

1/1-9/1979: very cold to cool (MJO mod 7-6)   (-PNA, -AO, neut NAO)

1/20-28/1991: cold/wintry (MJO mod 3-4)
(neut PNA, +AO, neut NAO)

1/4-14/1993: mild (MJO strong 8-1-2)
(-PNA, +AO, +NAO)

1/1-9/2005*: warm (MJO mod 4-5)
(-PNA, +AO, +NAO)

1/14-23/2009: very cold (MJO strong to mod 7-8-1)(+PNA, +AO, +NAO)

1/20-28/2014: very cold/wintry (MJO mod 6-7)
(+PNA, -AO, +NAO)

1/1-11/2015*: cold (MJO mod to strong 5-6) 
(neut PNA, +AO, +NAO)

1/1-8/2017: cold/wintry (MJO rt side COD)
(-PNA, +AO, neut NAO)

* = El Nino

 

 Analysis:

- 10 of 14 were cold

- 5 of 14 were wintry

- MJO: all over the map

- +PNA: all 4 very cold

- All mild to warm had -PNA but half the -PNAs cold

- Twice as many -PNA as +PNA

- -AO averaged colder (4 of 5 cold) than the more common +AO but 2/3 of +AO still cold

- Only 2 of 14 -NAO and one of those mild

- 6 of 7 neut NAO and 3 of 5 +NAO cold

 

Conclusions for upcoming -EPO:

- Having a -AO will favor cold

- Progged to have weaker -PNA than the 8 -PNAs listed. Thus, I don’t think it would prevent cold though it likely would prevent extreme cold.

- Better chance for cold without than with widespread significant wintry precip but that’s no surprise since it is the SE. But 5 of 14 (36%) being wintry beats the odds of most 8-12 day periods in Jan.

- And cold looking very likely per EPS. All 5 wintry cases were cold. That’s 5 of 11 (45%) cold cases being wintry. That’s high for the SE for an 8-12 day period in Jan!

-Weak -PNA would likely neither hurt nor enhance the wintry chance.

-If MJO is strong like what GEFS has, that may hurt wintry chance. Hoping MJO more like EPS.

-Oddly enough, -AO/-NAO surprisingly didn’t seem to help with wintry when considering these 14 cases fwiw though I’d still rather have them.

Anyone have the latest EPS (or any model) EPO forecast?

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1 hour ago, WinstonSalemArlington said:

GDMwK72WAAAXrI3?format=png&name=900x900

 

3 hours ago, GaWx said:

 So, the 0Z 1/4 EPS was forecasting a strong -EPO for mid Jan, the period I’m analyzing for SE winter storm chances. That would be a pretty big deal if it verifies. 80% of the moderate right side MJO with widespread SE mod to heavy wintry precip had a strong -EPO.

 This shows an 8 straight day period of sub -150. How often does that occur in any one winter? There have been 40 instances since 1948 or about one every other winter on average. No winter has had more than two. So, if that EPS is right, it would be a pretty big deal, especially when combined with a -AO. But this is all looking to go against a robust MC MJO.
 

 The lengthy strong EPO strings fully in Jan were (temps are for SE):

1/10-18/1957: cold (-PNA, +AO, neut NAO)

1/18-29/1961: very cold/wintry (+PNA, -AO, neut NAO)

1/15-22/1962: cold/wintry (-PNA, +AO, neut NAO)

1/9-31/1963: very cold (+PNA, -AO, -NAO)

1/17-26/1969*: slightly AN (-PNA, -AO, -NAO)

1/1-11/1974: mild (-PNA, +AO, neut NAO)

1/1-9/1979: very cold to cool (MJO mod 7-6)   (-PNA, -AO, neut NAO)

1/20-28/1991: cold/wintry (MJO mod 3-4)
(neut PNA, +AO, neut NAO)

1/4-14/1993: mild (MJO strong 8-1-2)
(-PNA, +AO, +NAO)

1/1-9/2005*: warm (MJO mod 4-5)
(-PNA, +AO, +NAO)

1/14-23/2009: very cold (MJO strong to mod 7-8-1)(+PNA, +AO, +NAO)

1/20-28/2014: very cold/wintry (MJO mod 6-7)
(+PNA, -AO, +NAO)

1/1-11/2015*: cold (MJO mod to strong 5-6) 
(neut PNA, +AO, +NAO)

1/1-8/2017: cold/wintry (MJO rt side COD)
(-PNA, +AO, neut NAO)

* = El Nino

 

 Analysis:

- 10 of 14 were cold

- 5 of 14 were wintry

- MJO: all over the map

- +PNA: all 4 very cold

- All mild to warm had -PNA but half the -PNAs cold

- Twice as many -PNA as +PNA

- -AO averaged colder (4 of 5 cold) than the more common +AO but 2/3 of +AO still cold

- Only 2 of 14 -NAO and one of those mild

- 6 of 7 neut NAO and 3 of 5 +NAO cold

 

Conclusions for upcoming -EPO:

- Having a -AO will favor cold

- Progged to have weaker -PNA than the 8 -PNAs listed. Thus, I don’t think it would prevent cold though it likely would prevent extreme cold.

- Better chance for cold without than with widespread significant wintry precip but that’s no surprise since it is the SE. But 5 of 14 (36%) being wintry beats the odds of most 8-12 day periods in Jan.

- And cold looking very likely per EPS. All 5 wintry cases were cold. That’s 5 of 11 (45%) cold cases being wintry. That’s high for the SE for an 8-12 day period in Jan!

-Weak -PNA would likely neither hurt nor enhance the wintry chance.

-If MJO is strong like what GEFS has, that may hurt wintry chance. Hoping MJO more like EPS.

-Oddly enough, -AO/-NAO surprisingly didn’t seem to help with wintry when considering these 14 cases fwiw though I’d still rather have them.

Anyone have the latest EPS (or any model) EPO forecast?

This looks to be playing out on the latest run with a few days of sub 30 degree temps after the over running event on 1/16. With another snow storm moving through the southeast as shown below. Would love 7 days of below freezing weather in south maybe kill some bugs ha!

Screenshot_20240106_220416_Chrome.jpg

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19 hours ago, SnowDawg said:

Last I saw was this from the Euro weeklies a couple days ago. IMG_0847.jpeg.be1052351f364fd26abc3935f0250ddd.jpeg

 The 0Z 1/7/24 EPS mean has maintained the Jan 11-18 period of near or sub -150 (-1.5) EPO that was on this 0Z 1/4/24 run. An 8+ day long period of -150 or lower has occurred about once every two winters on average since 1948 with no winter having more than two of them. The 0Z 1/7/24 EPS run is implying that the low of this period would probably be sub -300.

https://downloads.psl.noaa.gov/Public/map/teleconnections/epo.reanalysis.t10trunc.1948-present.txt

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