GFS Ensemble vs EPS

[TT-SEA]

Lets track this...

 

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

 

 

 

GFS ensemble mean at day 12:

 

[snow_wizard]

I like the GFS ensemble much more on this one.

[TT-SEA]

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.

[Phil]

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).

[Phil]

It’s suddenly become fluid. Lol.

[weatherfan2012]

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.

[Phil]

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..

[weatherfan2012]

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.

[TT-SEA]

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:

 

 

[Phil]

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:

 

 

Looks like they’re meeting in the middle.

[Front Ranger]

Looks like they’re meeting in the middle.

 

Well darn. Completely defeats the purpose of this thread.

[Jesse]

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.

[TT-SEA]

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.  

[TT-SEA]

Well darn. Completely defeats the purpose of this thread.

 

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

[Jesse]

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. 

[TT-SEA]

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.

[Front Ranger]

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

[Jesse]

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.

[TT-SEA]

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.  

[Jesse]

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

[TT-SEA]

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

 

 

 

 

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

 

 

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

 

 

 

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.

 

[Phil]

Looks like they’re meeting in the middle.

[TT-SEA]

 

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.

[Phil]

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.

[TT-SEA]

Update:

 

Where EPS started at 12 days out...

 

 

 

 

 

Where GFS ensembles started at 12 days out:

 

 

 

What it shows now:

 

 

 

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

 

GFS still moving towards EPS.

[Phil]

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

[TT-SEA]

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

Yes.

[Jesse]

https://youtu.be/Yd0fBXwDBmo

[TT-SEA]

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:

 

 

 

12Z GFS ensembles:

 

[Front Ranger]

Making progress!

[Phil]

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:

 

 

 

[TT-SEA]

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.    

[Phil]

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

[TT-SEA]

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.   

[Black Hole]

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

[TT-SEA]

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.   

[TT-SEA]

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.