Login to AccuWeather.com Premium Login to AccuWeather.com Professional Login to AccuWeather.com RadarPlus AccuWeather.com

Welcome Guest ( Log In | Register )

17 Pages V  « < 15 16 17  
Reply to this topicStart new topic
> 2017-2018 La Niņa watch, Forecasts and Discussions, long range.
grace
post Nov 13 2017, 07:58 PM
Post #321




Rank: F5 Superstorm
***

Group: Member
Posts: 11,192
Joined: 21-January 10
From: Paducah, Ky
Member No.: 21,017





QUOTE(ClicheVortex2014 @ Nov 9 2017, 05:48 PM) *
October 2010 500mb pattern vs October 2017 is just about as opposite as you can get... LOL. Love it. I hope future generations will appreciate (either as comedy or sympathetically) the struggle we go through today trying to figure this out





You're not kidding.

I looked at every Nina year (even -ENSO, -0.2 or better) October & found nothing close. You will not find a matching October since 1979 for sure. I haven't looked before then because of climo, but wouldn't hurt. Now if you expand it to maybe mid-Sept to mid-Nov you might but I haven't looked
Go to the top of the page
 
+Quote Post
ClicheVortex2014
post Nov 14 2017, 04:59 PM
Post #322




Rank: F5 Superstorm
***

Group: Member
Posts: 20,985
Joined: 21-April 14
From: Athens, Ohio
Member No.: 29,453





Nina looking quite healthy. A lot of cold water in the east ready to spread westward. Wonder how low region 3.4 will go.





This post has been edited by ClicheVortex2014: Nov 14 2017, 05:03 PM


--------------------
Meteorology undergrad at Ohio University

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978
- ILN Severe Weather Climatology

2017 Weather for Cincinnati

Days >90°: 11 (Last: 9/24/17)
Marginal risks: 18 (Last: 8/11/17)
Slight risks: 14 (Last: 8/22/17)
Enhanced risks: 7 (Last: 11/5/17)
Moderate risks: 0 (Last: 6/22/16)
High risks: 0 (Last: 11/17/13)

Realtime Weather on Campus: http://www.phy.ohiou.edu/~scalia/state_street/upload.png
Go to the top of the page
 
+Quote Post
ClicheVortex2014
post Nov 14 2017, 05:54 PM
Post #323




Rank: F5 Superstorm
***

Group: Member
Posts: 20,985
Joined: 21-April 14
From: Athens, Ohio
Member No.: 29,453





QUOTE(ClicheVortex2014 @ Nov 8 2017, 07:01 PM) *
Right. The placement is similar to what we saw last year. But here, I was responding to Grace who found a bunch of east-based Ninas of varying intensity. I was saying I'd like to look at the OLR of those years, and in a case such as that where you have a bunch of ENSO events of the same base but varying intensity, the position of the greatest OLR anomalies (which should be similar amongst them all if they all behaved as expected (e.g., east-based Nina -> east-based forcing)) is more important than the magnitude of OLR anomalies (which depend upon the strength of the Nina, which was not a part of the selection of ENSO events).

In other words, I still stand by my post regarding the forcing this year behaving like last year so far. The magnitude of the OLR does appear to be a bit weaker but the greatest anomalies are located around the same latitude.

Side point:
What's interesting is, although OLR has been weaker this year, MEI is stronger than last year. The value for AUG-SEP 2017 was -0.449, compared to -0.091 AUG-SEP 2016. Additionally, JUL-AUG 2017 to AUG-SEP 2017 featured a bigger drop (0.027 to -0.449) than JUL-AUG 2016 to AUG-SEP 2016 (0.186 to -0.091).

Regarding MEI... latest bimonthly numbers are in.

September/October 2017: -0.551 (up from -0.449)
September/October 2016: -0.363 (up from -0.091)

It's kind of an unfair comparison because this Nina is so much different from last year. Not only regarding the location of the Nina, but also the fact that we were almost 2 weeks past peak at this time last year. It looks like this Nina still has a solid 15-30+ days left until the Nina starts dying out.

NOAA has MEI ranks. Their definition:
QUOTE
How can one interpret these ranks? Given that there are 67-68 numbers in each column, the lowest
number (1) would denote the strongest La Nina case for that bimonthly season, while the highest
number (67 or 68) would indicate the strongest El Nino case. For instance, in December-January
(DECJAN), the strongest La Nina was recorded in 1974, while the strongest El Nino occurred in 1983.

If we use percentiles (say, the lower and upper 30%iles) to define La Nina and El Nino, respectively, MEI ranks from 1-21
denote strong to weak La Nina conditions,
while 47-67 (48-68) denote weak to strong El Nino conditions. If one uses the quintile definition for (moderate or stronger) ENSO events, MEI ranks from 1-14
would denote La Nina, while 54-67 (55-68) would denote El Nino. Finally, the comparison figures on this
website refer to strong ENSO events, such as might be defined by the top 7 (upper decile)
ranks, such as 1-7 for La Nina, and 61-67 (62-68) for El Nino.


In other words, focusing on Nina... you have a La Nina according to MEI if the rank is between 1-21. You have a moderate Nina if it's between 7-14. You have a strong Nina between 1-7.

September/October 2017 rank is 19.
August/September 2017 rank was 21.
September/October 2016 rank was 24. This was the lowest it got during the entire event.

https://www.esrl.noaa.gov/psd/enso/mei/rank.html


--------------------
Meteorology undergrad at Ohio University

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978
- ILN Severe Weather Climatology

2017 Weather for Cincinnati

Days >90°: 11 (Last: 9/24/17)
Marginal risks: 18 (Last: 8/11/17)
Slight risks: 14 (Last: 8/22/17)
Enhanced risks: 7 (Last: 11/5/17)
Moderate risks: 0 (Last: 6/22/16)
High risks: 0 (Last: 11/17/13)

Realtime Weather on Campus: http://www.phy.ohiou.edu/~scalia/state_street/upload.png
Go to the top of the page
 
+Quote Post
StL weatherjunki...
post Nov 16 2017, 11:25 AM
Post #324




Rank: F5 Superstorm
***

Group: Founding Member
Posts: 6,434
Joined: 10-June 07
From: Morgantown, WV
Member No.: 6,288





It's been a while since I brought up the 1999-2000 analog on here, but I'm sticking to my guns (i.e. similarities 2 years after a major El Nino event, particularly given ongoing moderate La Nina forcing) until I see a reason not to. A while back I mentioned what I though to be a ~1 month delay in the 2017 vs 1999 observed patterns and I'm going to continue with that rationale.

September 1999:
Attached File  Sept_1999_500mb.gif ( 15.7K ) Number of downloads: 1


October 2017:
Attached File  Oct_2017_500mb.gif ( 15.38K ) Number of downloads: 1


Yup, there are differences but I am arguing that the similarities are more noteworthy. For example, the banana ridge extending from Japan to the Pac NW / Gulf of Alaska. Additionally, note the weak troughing over the central US and potent ridging across the Northeast/Southeast Canada. If this were a good analog then October 1999 should give a good clue of November 2017:

October 1999:
Attached File  Oct_1999_500mb.gif ( 15.58K ) Number of downloads: 1


Early November 2017:
Attached File  Early_Nov_2017.gif ( 16.99K ) Number of downloads: 1


Current 8-10 day Euro forecast:
Attached File  11_16_00z_ECM.gif ( 141.88K ) Number of downloads: 0


Looks like general troughing over the Gulf of Alaska, ridging over the 4-corners/southern plains, and troughing over SE Canada are a reasonable match. Clearly there are differences in magnitude of ridging near the Bering Sea/North Atlantic as well as the precise locations of trough/ridge axes, but I'm curious how it will look by the end of the month.


--------------------
All model guidance is just that, guidance. It is the responsibility of the forecaster to take that information, make it better, and to appropriately communicate the forecast to the users.

Fervent supporter of the idea to make GFS output beyond hour 168 proprietary! Anyone wanting to post/share/tweet/etc GFS output beyond day 7 should have 1) a limited set of graphics available with the option to 2) contribute a nominal fee to get a full suite of products while improving future GFS output. #EURObusinessfor-the-win
Go to the top of the page
 
+Quote Post
ClicheVortex2014
post Yesterday, 12:59 AM
Post #325




Rank: F5 Superstorm
***

Group: Member
Posts: 20,985
Joined: 21-April 14
From: Athens, Ohio
Member No.: 29,453





For the first time in this event, all regions are below -1.0 anomaly on Tropicaltidbits page. Region 3 actually falls 0.23 short, but close enough.






Apparently quite a big spread westward. Here's what it all looks like



This post has been edited by ClicheVortex2014: Yesterday, 01:00 AM


--------------------
Meteorology undergrad at Ohio University

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978
- ILN Severe Weather Climatology

2017 Weather for Cincinnati

Days >90°: 11 (Last: 9/24/17)
Marginal risks: 18 (Last: 8/11/17)
Slight risks: 14 (Last: 8/22/17)
Enhanced risks: 7 (Last: 11/5/17)
Moderate risks: 0 (Last: 6/22/16)
High risks: 0 (Last: 11/17/13)

Realtime Weather on Campus: http://www.phy.ohiou.edu/~scalia/state_street/upload.png
Go to the top of the page
 
+Quote Post
grace
post Yesterday, 08:05 AM
Post #326




Rank: F5 Superstorm
***

Group: Member
Posts: 11,192
Joined: 21-January 10
From: Paducah, Ky
Member No.: 21,017





QUOTE(ClicheVortex2014 @ Nov 19 2017, 11:59 PM) *
For the first time in this event, all regions are below -1.0 anomaly on Tropicaltidbits page. Region 3 actually falls 0.23 short, but close enough.






Apparently quite a big spread westward. Here's what it all looks like




Also notice regions 1, 2, & 3 appear to have warmed quite a bit over last 7-10 days. Doesn't appear to be as much of a shift West, but rather a weakening of the Nina. Maybe temporary but that's what's happening. And of course since the waters are propagating from east to west, obviously the cooler waters out of those three regions are just now pushing into regions. 3.4 & 4.
Go to the top of the page
 
+Quote Post
ClicheVortex2014
post Yesterday, 10:34 PM
Post #327




Rank: F5 Superstorm
***

Group: Member
Posts: 20,985
Joined: 21-April 14
From: Athens, Ohio
Member No.: 29,453





QUOTE(grace @ Nov 20 2017, 08:05 AM) *
Also notice regions 1, 2, & 3 appear to have warmed quite a bit over last 7-10 days. Doesn't appear to be as much of a shift West, but rather a weakening of the Nina. Maybe temporary but that's what's happening. And of course since the waters are propagating from east to west, obviously the cooler waters out of those three regions are just now pushing into regions. 3.4 & 4.

How is this evidence of a weakening Nina when region 1+2 is the only region that has meaningfully warmed per Tropicaltidbits? And maybe it's not a shift west, but it's absolutely a spread west.

Furthermore, there's a difference between the SSTA graphs that Tropicaltidbits offers and the official CPC numbers. That's why I specified that in my original post because I see that as just a preliminary first-guess of where the official weekly numbers will go.

CODE
                Nino1+2      Nino3        Nino34        Nino4
Week          SST SSTA     SST SSTA     SST SSTA     SST SSTA
01NOV2017     20.4-0.8     24.4-0.6     26.3-0.4     28.7 0.1
08NOV2017     20.2-1.2     23.8-1.2     25.6-1.1     28.3-0.3
15NOV2017     20.6-1.0     23.8-1.1     25.6-1.1     28.2-0.4


It's also important to note that the regions that cooled are the regions that are most volatile.

There's been weakened trades in region 1+2, which explains the very slight warming in CPC's numbers.




I just don't see how you can call the overall Nina weakening, even temporarily weakening, with the data presented.

This post has been edited by ClicheVortex2014: Yesterday, 10:41 PM


--------------------
Meteorology undergrad at Ohio University

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978
- ILN Severe Weather Climatology

2017 Weather for Cincinnati

Days >90°: 11 (Last: 9/24/17)
Marginal risks: 18 (Last: 8/11/17)
Slight risks: 14 (Last: 8/22/17)
Enhanced risks: 7 (Last: 11/5/17)
Moderate risks: 0 (Last: 6/22/16)
High risks: 0 (Last: 11/17/13)

Realtime Weather on Campus: http://www.phy.ohiou.edu/~scalia/state_street/upload.png
Go to the top of the page
 
+Quote Post
MaineJay
post Today, 05:10 AM
Post #328




Rank: F5 Superstorm
***

Group: Member
Posts: 8,229
Joined: 15-February 13
From: 25 mi. NNW of Portland, ME, elev. ~400ft.
Member No.: 28,288





In my humble opinion, we are seeing a bit of an "acceleration" of this Niņa evolution. I'll explain.

I've been waiting to see if that MJO wave in October was sufficient to initiate Kelvin wave activity. After looking at the observations, I believe that at least some EKW activity has begun, but the magnitude isn't great.

First is Tao data, this shows the sub surface warm tongue pushing east.
Attached File  ezgif_4_0848c76b21.gif ( 113.12K ) Number of downloads: 0

https://www.pmel.noaa.gov/gtmba/assorted-plots

Similar to a digging trof, or a boat pushing through water, the "downwelling" action creates an "upwelling" just out in front. So I believe the downwelling west of the dateline is aiding in the upwelling to the east of it.

HYCOM also shows an uptick in EKW activity.

Attached File  ezgif_4_e5e963e488.gif ( 925.49K ) Number of downloads: 0

https://www7320.nrlssc.navy.mil/GLBhycomcic...ast_anim30d.gif

Since SSTs only really show what's going on at the very ocean surface, sea surface heights can give a bit more context.

Again, the rising of sea surface heights in the west Pacific suggests a Kelvin wave.
Attached File  ezgif_4_26e77de910.gif ( 325.41K ) Number of downloads: 0

https://sealevel.jpl.nasa.gov/science/elnin...stdata/archive/


So, any weakening in the trades (even very weak enhanced trades) in the area I boxed out, will encourage this Kelvin wave activity. Remember, there's always a slope to the equatorial Pacific, and it's currently double the normal in this region.


Attached File  20171121_045802.png ( 53.46K ) Number of downloads: 0


http://tao.ndbc.noaa.gov/refreshed/index.php

This post has been edited by MaineJay: Today, 05:44 AM


--------------------
Maybe the hokey pokey really is what it's all about.

Go to the top of the page
 
+Quote Post
grace
post Today, 06:42 AM
Post #329




Rank: F5 Superstorm
***

Group: Member
Posts: 11,192
Joined: 21-January 10
From: Paducah, Ky
Member No.: 21,017





QUOTE(ClicheVortex2014 @ Nov 20 2017, 09:34 PM) *
How is this evidence of a weakening Nina when region 1+2 is the only region that has meaningfully warmed per Tropicaltidbits? And maybe it's not a shift west, but it's absolutely a spread west.

Furthermore, there's a difference between the SSTA graphs that Tropicaltidbits offers and the official CPC numbers. That's why I specified that in my original post because I see that as just a preliminary first-guess of where the official weekly numbers will go.

CODE
                Nino1+2      Nino3        Nino34        Nino4
Week          SST SSTA     SST SSTA     SST SSTA     SST SSTA
01NOV2017     20.4-0.8     24.4-0.6     26.3-0.4     28.7 0.1
08NOV2017     20.2-1.2     23.8-1.2     25.6-1.1     28.3-0.3
15NOV2017     20.6-1.0     23.8-1.1     25.6-1.1     28.2-0.4


It's also important to note that the regions that cooled are the regions that are most volatile.

There's been weakened trades in region 1+2, which explains the very slight warming in CPC's numbers.




I just don't see how you can call the overall Nina weakening, even temporarily weakening, with the data presented.



Agree! Spread west better statement
Go to the top of the page
 
+Quote Post
so_whats_happeni...
post Today, 03:23 PM
Post #330




Rank: F5 Superstorm
***

Group: Member
Posts: 13,861
Joined: 23-March 08
From: Millersville, PA
Member No.: 14,460





QUOTE(MaineJay @ Nov 21 2017, 07:10 AM) *
In my humble opinion, we are seeing a bit of an "acceleration" of this Niņa evolution. I'll explain.

I've been waiting to see if that MJO wave in October was sufficient to initiate Kelvin wave activity. After looking at the observations, I believe that at least some EKW activity has begun, but the magnitude isn't great.

First is Tao data, this shows the sub surface warm tongue pushing east.
Attached File  ezgif_4_0848c76b21.gif ( 113.12K ) Number of downloads: 0

https://www.pmel.noaa.gov/gtmba/assorted-plots

Similar to a digging trof, or a boat pushing through water, the "downwelling" action creates an "upwelling" just out in front. So I believe the downwelling west of the dateline is aiding in the upwelling to the east of it.

HYCOM also shows an uptick in EKW activity.

Attached File  ezgif_4_e5e963e488.gif ( 925.49K ) Number of downloads: 0

https://www7320.nrlssc.navy.mil/GLBhycomcic...ast_anim30d.gif

Since SSTs only really show what's going on at the very ocean surface, sea surface heights can give a bit more context.

Again, the rising of sea surface heights in the west Pacific suggests a Kelvin wave.
Attached File  ezgif_4_26e77de910.gif ( 325.41K ) Number of downloads: 0

https://sealevel.jpl.nasa.gov/science/elnin...stdata/archive/
So, any weakening in the trades (even very weak enhanced trades) in the area I boxed out, will encourage this Kelvin wave activity. Remember, there's always a slope to the equatorial Pacific, and it's currently double the normal in this region.
Attached File  20171121_045802.png ( 53.46K ) Number of downloads: 0


http://tao.ndbc.noaa.gov/refreshed/index.php


Yea been thinking this for a bit now it seems as though the last MJO initiated something but failed to really couple up with it. I tend to agree we may see one of two things happen, one we could see another MJO spark up and help move this wave eastward with time and kind of stall the strengthening and maybe even weaken the nina state a little bit. Two we could see it sharpen real quick drop in a more localized area instead of spread over the basin and then begin to dwindle around maybe mid december either way it seems we are at about the peak of this event unless something throws a surprise out there.


--------------------
Tylor Cartter

B.S. in Meteorology
Millersville University


Weather Observer:
KMDT: Harrisburg International Airport
KBWI: Baltimore/ Washington International Airport

Stratosphere Discussion:
2016/2017
2017/2018


AccuWeather Forum MidAtl/NE Snowfall Forecasting Champion Winter 2017
Go to the top of the page
 
+Quote Post
idecline
post Today, 08:45 PM
Post #331




Rank: F5 Superstorm
***

Group: Member
Posts: 19,094
Joined: 27-May 10
From: uncertain
Member No.: 22,866





...idee knows that some do not 'get' this 3-D view of the tropical Pacific Ocean...but very informative...
Attached File  frame060.png ( 34.79K ) Number of downloads: 0


...this shows SST's and temperatures to and below the thermocline...it also shows how much water builds up in the west Pacific courtesy of the strong convection center near Indonesia...and the prevailing trade winds...

...MJ (above) has valid points about the Nina perhaps peaking or past-peak and ... idee's gut feels a OKW...

...also notice the colder edge of the water is facing south...towards the end of their(south Hemisphere) Boreal Spring...the upwelling along the S.America coast should wane as their weather slows down into their Spring into Summer...a sloshback is well overdue...yet who knows... huh.gif unsure.gif


--------------------

"Science cannot solve the ultimate mystery of nature. And that is because, in the last analysis, we ourselves are part of nature and therefore part of the mystery that we are trying to solve."
- Max Planck

Go to the top of the page
 
+Quote Post

17 Pages V  « < 15 16 17
Reply to this topicStart new topic
4 User(s) are reading this topic (3 Guests and 0 Anonymous Users)
1 Members: djbq39

 

RSS Lo-Fi Version Time is now: 21st November 2017 - 10:51 PM