• Hello, please take a minute to check out our awesome content, contributed by the wonderful members of our community. We hope you'll add your own thoughts and opinions by making a free account!

Pattern December Discussion

Storm5 link said:
damn that's a very interesting gfs run . Lots of possibilities

Sent from my SM-G900V using Tapatalk
Click to expand...
Lol! JB, is that you?? I like the positive vibe!
 
Has the 12Z GFS run all of the way out to 384? I see it only to 234 on Tidbits.

Edit: NM. Now all of the way out to 384.
 
GaWx link said:
Has the 12Z GFS run all of the way out to 384? I see it only to 234 on Tidbits.

Edit: NM. Now all of the way out to 384.
Click to expand...

Yes, this is 384

gfs_mslp_pcpn_frzn_us_52.png
 
Re: December Discussion

12z gefs is the most agressive run yet for the Arkansas mississippi west tenn area for wintry precip Sunday -Tuesday period

Sent from my SM-G900V using Tapatalk
 
Re: December Discussion

Storm5 link said:
12z gefs is the most agressive run yet for the Arkansas mississippi west tenn area for wintry precip Sunday -Tuesday period

Sent from my SM-G900V using Tapatalk
Click to expand...

:mad:
 
Brick Tamland link said:
Good trend with the GFS.
Click to expand...
Yeah, if I lived in Memphis, I'd be ecstatic!
The Carolinas, not so much
 
Tarheel1 link said:
[quote author=Brick Tamland link=topic=2.msg1738#msg1738 date=1481650086]
Good trend with the GFS.
Click to expand...
Yeah, if I lived in Memphis, I'd be ecstatic!
The Carolinas, not so much
[/quote]

Its not that bad on 40W
 
Webberweather53 link said:
[quote author=GaStorm link=topic=2.msg1704#msg1704 date=1481640381]
[quote author=Webberweather53 link=topic=2.msg1700#msg1700 date=1481638770]
I wouldn't be surprised to see the massive/poleward Aleutian ridge return by the 1st-2nd week of January once the tropical forcing shifts back into the Indian Ocean forcing the Pacific jet to retract again. We're in a QBO/ENSO base state (WQBO/-ENSO) that favors a high-latitude Aleutian/far North Pacific ridge, and tropical pacific forcing in this background will only act to suppress the ridge into the central Pacific, therefore causing a stronger than normal Pacific jet to enforce mild/Pacific air across North America. Even though the polar vortex is liable to recover somewhat in the near-term, the redevelopment of the Scanadinavian Ridge-Alaskan vortex configuration should cause WAFz (wave activity flux) to increase again in the medium-long range, thus at least giving us a chance to get another -AO surge later in January if we get can sustain that and get enough tropospheric forcing @ the right time to get a huge lobe of the polar vortex to sit over North America. As far as I'm concerned, if we don't see a nice PV lobe over North America in January &/or February, we're going to probably have issues wrt getting cold air into the east-central US. January is highly uncertain wrt its sensible impacts, but I'd lean above average here if anything. I'm not holding out much hope for February this year given the nearly unanimous signals for warmth in that month from the climate models, analogs, and the canonical QBO/ENSO progression, but we shall see.

I produced this graphic several weeks ago when I made my winter forecast, thus far I'm fairly pleased w/ how December has played out, the blend of these 3 sets of years seemed to be the most realistic route. As you can probably tell, there's a lot of uncertainty w/ January, but pretty remarkable consensus on a warm February here.
Click to expand...

If the Nina fades fast I wouldn't count out February yet.
[/quote]

I actually don't think that really matters terribly much whether we end up w/ a weak NINA or significant cool neutral ENSO event, the inter-event variability wrt the sensible impacts of these phases of ENSO is the largest amongst all ENSO types, hence ENSO's overall role (although significant) can be rather elusive in a weak NINA-cool neutral, but I will say when I experimented w/ a cool neutral ENSO background state, the same temperature distributions remained (warm SE, cool NW) but they were a bit tempered. Even if the NINA completely collapses right now, it would take a few months or more for its impacts to run their course throughout the overall climate system. The NCEP/NCAR Reanalysis Multivariate ENSO Index (MEI) & Adjusted, Pentad Averaged Bivariate ENSO Timeseries (BEST) indices i'm currently running were both in weak NINA territory last month. The twin westerly QBO regimes is definitely helping prop up this event via enhancement of off-equatorial convection (& thus the SE Asia & Australian monsoon circulations) & if we maintain a WQBO regime through this fall, I would expect La Nina conditions to return next year, w/ potentially a stronger event than this year in 2017-18, but if EQBO finally makes an appearance, then we may crawl towards neutral or warm neutral, but I'm doubtful of the latter scenario atm...
There's no denying that a weaker NINA event going into the late portions of this winter would certainly help to some extent to take some of the edge off the canonical NINA progression w/ a warmer than normal SE US in FEB but I'm not sure about its significance.

Adjusted, Pentad Averaged BEST Index ranks (1870-Present)
http://weatheradvance.com/home/weather/weatheradvance.com/wp-content/uploads/2016/12/Adjusted-Bivariate-ENSO-Timeseries-BEST-Index-Rankings-1870-Present.txt

NCEP/NCAR Reanalysis Multivariate ENSO Index (MEI) data and ranks (1948-Present)
http://weatheradvance.com/home/weather/weatheradvance.com/wp-content/uploads/2016/12/NCEPNCAR-Multivariate-ENSO-Index-MEI-Raw-Data-Rankings-1948-present-v2.0.txt
[/quote]

I have heard that it will prolong winter if it briefly gains weak Nina status and then rapidly fades which has been discussed recently. DT also mentions this as well in his winter forecast as well. See below.

Another image we can view is the NMME enso forecast model projections from mid July into the Spring of 2017.  This image shows 8  of the main climate models and most the data shows weak La Nina developing during the Autumn but weakening steadily and fairly rapidly throughout the Winter.  This would seem to favor a somewhat milder than normal autumn but potentially a colder than normal and stormy of the normal winter for the central and eastern U.S..

https://www.wxrisk.com/1st-speculation-of-winter-2016-2017/
 
Webberweather53 link said:
I wouldn't be surprised to see the massive/poleward Aleutian ridge return by the 1st-2nd week of January once the tropical forcing shifts back into the Indian Ocean forcing the Pacific jet to retract again. We're in a QBO/ENSO base state (WQBO/-ENSO) that favors a high-latitude Aleutian/far North Pacific ridge, and tropical pacific forcing in this background will only act to suppress the ridge into the central Pacific, therefore causing a stronger than normal Pacific jet to enforce mild/Pacific air across North America. Even though the polar vortex is liable to recover somewhat in the near-term, the redevelopment of the Scanadinavian Ridge-Alaskan vortex configuration should cause WAFz (wave activity flux) to increase again in the medium-long range, thus at least giving us a chance to get another -AO surge later in January if we get can sustain that and get enough tropospheric forcing @ the right time to get a huge lobe of the polar vortex to sit over North America. As far as I'm concerned, if we don't see a nice PV lobe over North America in January &/or February, we're going to probably have issues wrt getting cold air into the east-central US. January is highly uncertain wrt its sensible impacts, but I'd lean above average here if anything. I'm not holding out much hope for February this year given the nearly unanimous signals for warmth in that month from the climate models, analogs, and the canonical QBO/ENSO progression, but we shall see.

I produced this graphic several weeks ago when I made my winter forecast, thus far I'm fairly pleased w/ how December has played out, the blend of these 3 sets of years seemed to be the most realistic route. As you can probably tell, there's a lot of uncertainty w/ January, but pretty remarkable consensus on a warm February here.

Pardon me if the picture is cut-off I did my best to resize
Click to expand...

Eric, is that you?
 
SD link said:
[quote author=Tarheel1 link=topic=2.msg1742#msg1742 date=1481650962]
[quote author=Brick Tamland link=topic=2.msg1738#msg1738 date=1481650086]
Good trend with the GFS.
Click to expand...
Yeah, if I lived in Memphis, I'd be ecstatic!
The Carolinas, not so much
[/quote]

Its not that bad on 40W
[/quote]

I think it's a step in the right direction, though. Better than going the other way.
 
12z euro has freezing rain Memphis into northern miss and NW Alabama  Sunday afternoon ....light

Sent from my SM-G900V using Tapatalk
 
SD link said:
[quote author=packfan98 link=topic=2.msg1756#msg1756 date=1481654101]
Euro looks pretty dry to me for this weekend and next week.
Click to expand...

Looks like its about to fire up some freezing rain around 6z Tuesday
[/quote]
yep freezing rain for central NC Tuesday

Sent from my SM-G900V using Tapatalk
 
GaStorm link said:
[quote author=Webberweather53 link=topic=2.msg1707#msg1707 date=1481641459]
[quote author=GaStorm link=topic=2.msg1704#msg1704 date=1481640381]
[quote author=Webberweather53 link=topic=2.msg1700#msg1700 date=1481638770]
I wouldn't be surprised to see the massive/poleward Aleutian ridge return by the 1st-2nd week of January once the tropical forcing shifts back into the Indian Ocean forcing the Pacific jet to retract again. We're in a QBO/ENSO base state (WQBO/-ENSO) that favors a high-latitude Aleutian/far North Pacific ridge, and tropical pacific forcing in this background will only act to suppress the ridge into the central Pacific, therefore causing a stronger than normal Pacific jet to enforce mild/Pacific air across North America. Even though the polar vortex is liable to recover somewhat in the near-term, the redevelopment of the Scanadinavian Ridge-Alaskan vortex configuration should cause WAFz (wave activity flux) to increase again in the medium-long range, thus at least giving us a chance to get another -AO surge later in January if we get can sustain that and get enough tropospheric forcing @ the right time to get a huge lobe of the polar vortex to sit over North America. As far as I'm concerned, if we don't see a nice PV lobe over North America in January &/or February, we're going to probably have issues wrt getting cold air into the east-central US. January is highly uncertain wrt its sensible impacts, but I'd lean above average here if anything. I'm not holding out much hope for February this year given the nearly unanimous signals for warmth in that month from the climate models, analogs, and the canonical QBO/ENSO progression, but we shall see.

I produced this graphic several weeks ago when I made my winter forecast, thus far I'm fairly pleased w/ how December has played out, the blend of these 3 sets of years seemed to be the most realistic route. As you can probably tell, there's a lot of uncertainty w/ January, but pretty remarkable consensus on a warm February here.
Click to expand...

If the Nina fades fast I wouldn't count out February yet.
[/quote]

I actually don't think that really matters terribly much whether we end up w/ a weak NINA or significant cool neutral ENSO event, the inter-event variability wrt the sensible impacts of these phases of ENSO is the largest amongst all ENSO types, hence ENSO's overall role (although significant) can be rather elusive in a weak NINA-cool neutral, but I will say when I experimented w/ a cool neutral ENSO background state, the same temperature distributions remained (warm SE, cool NW) but they were a bit tempered. Even if the NINA completely collapses right now, it would take a few months or more for its impacts to run their course throughout the overall climate system. The NCEP/NCAR Reanalysis Multivariate ENSO Index (MEI) & Adjusted, Pentad Averaged Bivariate ENSO Timeseries (BEST) indices i'm currently running were both in weak NINA territory last month. The twin westerly QBO regimes is definitely helping prop up this event via enhancement of off-equatorial convection (& thus the SE Asia & Australian monsoon circulations) & if we maintain a WQBO regime through this fall, I would expect La Nina conditions to return next year, w/ potentially a stronger event than this year in 2017-18, but if EQBO finally makes an appearance, then we may crawl towards neutral or warm neutral, but I'm doubtful of the latter scenario atm...
There's no denying that a weaker NINA event going into the late portions of this winter would certainly help to some extent to take some of the edge off the canonical NINA progression w/ a warmer than normal SE US in FEB but I'm not sure about its significance.

Adjusted, Pentad Averaged BEST Index ranks (1870-Present)
http://weatheradvance.com/home/weather/weatheradvance.com/wp-content/uploads/2016/12/Adjusted-Bivariate-ENSO-Timeseries-BEST-Index-Rankings-1870-Present.txt

NCEP/NCAR Reanalysis Multivariate ENSO Index (MEI) data and ranks (1948-Present)
http://weatheradvance.com/home/weather/weatheradvance.com/wp-content/uploads/2016/12/NCEPNCAR-Multivariate-ENSO-Index-MEI-Raw-Data-Rankings-1948-present-v2.0.txt
[/quote]

I have heard that it will prolong winter if it briefly gains weak Nina status and then rapidly fades which has been discussed recently. DT also mentions this as well in his winter forecast as well. See below.

Another image we can view is the NMME enso forecast model projections from mid July into the Spring of 2017.  This image shows 8  of the main climate models and most the data shows weak La Nina developing during the Autumn but weakening steadily and fairly rapidly throughout the Winter.  This would seem to favor a somewhat milder than normal autumn but potentially a colder than normal and stormy of the normal winter for the central and eastern U.S..

https://www.wxrisk.com/1st-speculation-of-winter-2016-2017/
[/quote]

I see what DT is saying, but after looking at the two sets of years myself, I don't see how the two patterns (weakening weak-moderate NINAs & strengthening weak-moderate NINAs) are that much different. I performed a t test on the standardized, 30-year sliding temperature anomalies in NC & the results weren't really significant at all, although the pattern w/ weakening weak-moderate NINAs was just ever so slightly cooler (not by much), this difference could be attributed to a multitude of non-physical human errors and processes such as the sensitivity of the dataset used, small sample size, etc.
 
You must log in or register to reply here.
Back
Top