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GFS Ensemble vs EPS

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#1
TT-SEA

Posted 17 March 2018 - 12:30 PM

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Lets track this...

 

12Z EPS mean from 3/17 for day 12 (3/29):

 

eps_t850a_noram_49_1.png

 

 

GFS ensemble mean at day 12:

 

gefs_t850a_noram_49.png



#2
snow_wizard

Posted 17 March 2018 - 12:57 PM

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I like the GFS ensemble much more on this one.


Death To Warm Anomalies!

 

Winter 2018-19 stats

 

Total Snowfall = 0.0"

Coldest Low = 27

Lows 32 or below = 7

Highs 32 or below = 0

Lows Below 20 = 0

Highs 40 or below = 0

 

 


#3
TT-SEA

Posted 17 March 2018 - 01:18 PM

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I like the GFS ensemble much more on this one.


And its been playing this too cold game for almost a month. The EPS has been so much more consistent with everything... cold and warm.

#4
Phil

Posted 17 March 2018 - 04:23 PM

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The EPS looks closer to what I think will happen. The exact timing is always questionable, though.

The GEFS looks closer to what I think the pattern will morph into during early/mid April. The SE-ridge will probably be stronger, though (IMO).
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#5
Phil

Posted 18 March 2018 - 02:17 AM

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It’s suddenly become fluid. Lol.
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#6
weatherfan2012

Posted 18 March 2018 - 07:12 AM

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It’s suddenly become fluid. Lol.

I feel for the Mets on this storm as there really is no easy answer until it's right on top of us and the fact many want the answers now really compounds the challenges of this forecasts.

#7
Phil

Posted 18 March 2018 - 07:52 AM

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I feel for the Mets on this storm as there really is no easy answer until it's right on top of us and the fact many want the answers now really compounds the challenges of this forecasts.


I expect white rain until proven otherwise. Since the surface low will be disjointed from the 500mb low, the thermals aloft will be borderline. Therefore it will need to puke like a mofo to accumulate on anything other than grassy surfaces.

Getting pavement accumulation with temperatures in the upper 30’s was hard enough during early February. Now we’ll need to pull it off at the spring equinox, after a stretch of 55*F weather and pounding sunshine. Lol..
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#8
weatherfan2012

Posted 18 March 2018 - 08:03 AM

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I expect white rain until proven otherwise. Since the surface low will be disjointed from the 500mb low, the thermals aloft will be borderline. Therefore it will need to puke like a mofo to accumulate on anything other than grassy surfaces.
Getting pavement accumulation with temperatures in the upper 30’s was hard enough during early February. Now we’ll need to pull it off at the spring equinox, after a stretch of 55*F weather and pounding sunshine. Lol..

agreed plus I think the fact this winter snow season was so lame many are ungoreing the negative factors just so this storm would be the one that break the trend so to speak.

#9
TT-SEA

Posted 19 March 2018 - 05:30 AM

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Update:

 

(note - the GFS ensemble map at 252 hours was messed up and had inverted colors on WB so I am using the afternoon of the same day for both)

 

EPS:

 

eps_t850a_noram_45_1.png

 

gefs_t850a_noram_45.png



#10
Phil

Posted 19 March 2018 - 09:20 AM

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Update:

(note - the GFS ensemble map at 252 hours was messed up and had inverted colors on WB so I am using the afternoon of the same day for both)

EPS:

eps_t850a_noram_45_1.png

gefs_t850a_noram_45.png


Looks like they’re meeting in the middle.
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#11
Front Ranger

Posted 19 March 2018 - 09:27 AM

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Looks like they’re meeting in the middle.

 

Well darn. Completely defeats the purpose of this thread.


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Cool anomalies soothe the soul.


#12
Jesse

Posted 19 March 2018 - 09:28 AM

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Looks like they’re meeting in the middle.


I would say the EPS has moved toward the GFS ensemble, which basically looks the same as it did a few days ago.

#13
TT-SEA

Posted 19 March 2018 - 10:29 AM

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I would say the EPS has moved toward the GFS ensemble, which basically looks the same as it did a few days ago.

 

GFS has moved a little towards the ECMWF as well.  



#14
TT-SEA

Posted 19 March 2018 - 10:30 AM

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Well darn. Completely defeats the purpose of this thread.

 

Not really... its interesting regardless of the outcome.  



#15
Jesse

Posted 19 March 2018 - 10:33 AM

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GFS has moved a little towards the ECMWF as well.  

 

The GEFS maybe took one pace while the EPS took like five.

 

Just crazy to see the GFS leading the way on a big pattern change like this. I will admit I am a little proud of our domestic model. 



#16
TT-SEA

Posted 19 March 2018 - 10:41 AM

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The GEFS maybe took one pace while the EPS took like five.

 

Just crazy to see the GFS leading the way on a big pattern change like this. I will admit I am a little proud of our domestic model. 

 

I am not sure the EPS moved that much towards the GFS.   

 

Its still warm along the West Coast and the center of the real cold air in Canada is smaller and not any closer.



#17
Front Ranger

Posted 19 March 2018 - 10:50 AM

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Not really... its interesting regardless of the outcome.


;)

Cool anomalies soothe the soul.


#18
Jesse

Posted 19 March 2018 - 11:02 AM

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I am not sure the EPS moved that much towards the GFS.   

 

Its still warm along the West Coast and the center of the real cold air in Canada is smaller and not any closer.

 

I wish objectivity wasn't such a one way street with you.



#19
TT-SEA

Posted 19 March 2018 - 11:12 AM

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I wish objectivity wasn't such a one way street with you.

 

The EPS did not trend closer with the core of the cold air in Canada.

 

The main players are in the same basic position on the EPS.    The area of really cold air in northern Canada is shrinking a little and the warm anomalies offshore are a little more robust.   

 

Its not making some dramatic move at that time towards much colder like you are implying.    You can also try being objective.  



#20
Jesse

Posted 19 March 2018 - 11:20 AM

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The EPS did not trend closer with the core of the cold air in Canada.

The main players are in the same basic position on the EPS. The area of really cold air in northern Canada is shrinking a little and the warm anomalies offshore are a little more robust.

Its not making some dramatic move at that time towards much colder like you are implying. You can also try being objective.


#nospinzone

#21
TT-SEA

Posted 20 March 2018 - 11:58 AM

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Update from the 12Z runs... EPS is not wavering at all for the day we have been tracking (3/29).

 

 

eps_t850a_noram_39.png

 

 

For reference... here is where the EPS started:

 

eps_t850a_noram_49_1.png

 

GFS ensemble mean is slowly coming into line... warm air is shown farther east with each run. 

 

gefs_t850a_noram_39.png

 

 

For reference... here is where the GFS started.   I am guessing it will shift farther east again over the next couple days and finally be in agreement once we get within 6 or 7 days.

 

gefs_t850a_noram_49.png



#22
Phil

Posted 20 March 2018 - 12:02 PM

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Looks like they’re meeting in the middle.


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#23
TT-SEA

Posted 20 March 2018 - 12:09 PM

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Looks like they’re meeting in the middle.

 

 

 

Then I guess the "middle" is going to end up warm for us.    ;)

 

We started with the EPS showing warm for us... and the GFS being quite cold (as it always seems to be in the long range lately).  Very different weather locally.

 

We will very likely end up being warm on that day... if that happens then I am going to give it to the model that showed it being warm.   That would be the EPS. 

 

This all started because people were posting about the cold, wet, and troughy GFS ensembles as if they were going to verify... and I said the EPS consistently showed the cold trough for later this week and weekend and then consistently showed a ridge and warmer air moving in next week.    Very hard to argue against the EPS at this point.



#24
Phil

Posted 20 March 2018 - 12:34 PM

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Look at the orientation of the ridge/trough axes. It’s really is a compromise on the pattern.

FWIW, I don’t think the early April ridgy period was ever in question. It’s been a high-probability outcome for awhile now, IMO.
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#25
TT-SEA

Posted 21 March 2018 - 01:43 PM

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Update:

 

Where EPS started at 12 days out...

 

eps_t850a_noram_49_1.png

 

eps_t850a_noram_33.png

 

 

 

Where GFS ensembles started at 12 days out:

 

gefs_t850a_noram_49.png

 

 

What it shows now:

 

gefs_t850a_noram_33.png

 

 

EPS is not wavering... anomalies are getting stronger as the time approaches as expected.

 

GFS still moving towards EPS.



#26
Phil

Posted 21 March 2018 - 02:19 PM

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Huh? The EPS totally flopped over NE Canada and Alaska. Unless you’re just talking about your region?
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#27
TT-SEA

Posted 21 March 2018 - 03:03 PM

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Huh? The EPS totally flopped over NE Canada and Alaska. Unless you’re just talking about your region?


Yes.

#28
Jesse

Posted 23 March 2018 - 09:06 AM

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https://youtu.be/Yd0fBXwDBmo
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#29
TT-SEA

Posted 23 March 2018 - 11:40 AM

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Update from 12Z runs... GFS ensemble mean sure came around to the EPS for our test day.   They now agree since its only 6 days out.

 

12Z EPS:

 

eps_t850a_noram_27.png

 

 

12Z GFS ensembles:

 

gefs_t850a_noram_27.png



#30
Front Ranger

Posted 23 March 2018 - 11:59 AM

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Making progress!


Cool anomalies soothe the soul.


#31
Phil

Posted 23 March 2018 - 05:00 PM

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Update from 12Z runs... GFS ensemble mean sure came around to the EPS for our test day. They now agree since its only 6 days out.


Dude..this is some insane cherrypicking. In reality, each of the 5-day blocks on the 18z GEFS are colder than average across the PNW:

Days 1-5, days 6-10, and days 11-15:

K3UZJKS.png

oVPmNL5.png

FFq6Zlp.png
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#32
TT-SEA

Posted 23 March 2018 - 06:41 PM

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I am not making a forecast here.   I am not talking about where the pattern is going in the thread.  

 

I am tracking how the EPS and GFS ensembles evolved for one specific day as test.     That was all I ever intended with this little experiment.    Every post will be looking at 3/29.

 

We started 12 days out and are now within 6 days.   I wanted to see how they trend for that day and score the actual results when that day arrives.   

 

This is not an ongoing thread.   It will end on Thursday.   We could start another thread though for ongoing comparisons... might be a good for reference.    



#33
Phil

Posted 23 March 2018 - 08:01 PM

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That’s a head scratcher to me, but fair enough.
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#34
TT-SEA

Posted 23 March 2018 - 09:54 PM

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That’s a head scratcher to me, but fair enough.

 

Ever had a forecast contest?    It specific to a day.  :)

 

Obviously what happens next weekend an beyond is a much more interesting wild card now.   



#35
Black Hole

Posted 28 March 2018 - 03:28 PM

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Tomorrow is the validation day. EPS was closer, at least for my area. 


BS Atmospheric Science University of Utah May 2015

PhD Candidate Atmospheric Sciences

 

--Emphasis on: Forecasting, Mountain Weather, Numerical Weather Prediction, Data Assimilation

 

Winter 2017/2018

Dec 4: 3.2", 16: 0.9", 20: 2.1", 23: 1.5", 25: 4.6"

Jan 6: 1.5", 20: 10.8", 25: 1.5"

Feb 19: 8.6", 20: 2.4", 23: 7.1", 25: .5"

Mar 4: 13", 15: 1.8", 17: 5.3", 25: 4.2"

April 12: 1", 17: 1.3"

Total: 69.3"

 

 

Winter 2016/17 Snow:
Nov 17: 3.2", 23: 1.6", 28: 9.2" (14)

Dec 1: .5", 16: 2.5", 25: 13" (16)

Jan 2: 5", 3: 2.4", 4: 7.7", 12: 1", 19: 1.2", 21: 13", 23: 6", 24: 1", 25: 3.7", 26: 2.5" (43.5) 

Feb 11: .5", 23: 6.5", 27: 4.5" (13.5)

Mar 5: 5.5" (5.5)

Apr 8: 2", 9: 1.8" (3.8)

May 17: 1" (1)
Total: 96.3"

Lowest Temp: 2F


#36
TT-SEA

Posted 28 March 2018 - 03:36 PM

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No doubt that the GFS ensembles won this battle.   Hands down.  

 

I was 100% wrong in my theory.    I guess that was the point of the test though.   



#37
TT-SEA

Posted 29 March 2018 - 01:01 PM

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The actual result today... I say the GFS ensemble mean won overall.    Looking back... both models ended up pretty close though at about one week out.  

 

gfs_T850a_namer_3.png