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GFS vs EURO

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GFS vs EURO Empty GFS vs EURO

Post by amugs Wed Mar 19, 2014 8:09 pm

I found this on another site and it was produced by a woman with good credentials IMO

http://www.energyblogs.com/weather/index.cfm/2014/1/6/Differences-Between-the-GFS-and-ECMWF-Weather-Models

http://www.energyblogs.com/weather/bio.cfm


Posted At : January 6, 2014 10:27 PM | Posted By : Ria Persad
Related Categories: Clean Power Investing, Demand Management, Energy Storage, Fossil & Biomass, Outage Management, Risk & Operations
Most energy professionals receive weather information stemming from government models. The two government numerical weather prediction models most commonly employed in the U.S. energy markets are the GFS (American) and the ECMWF (European) ensembles. I receive many questions on the differences between these two models, so after a long literature search, corroborated by my own experience, I compiled this quick reference for energy professionals and weather enthusiasts. These generalities will not work every time, as there will be exceptions, but I have done my best to summarize the most current findings from a number of prominent scientists. If you are aware of new or different information than what is here, please feel free to email me at rpersad@statweather.com and I will update this list. If you are interested in long-range prediction models (beyond the 16-day range of the GFS and ECMWF ensembles), please go to WWW.STATWEATHER.COM to learn more about long-range forecasting.

DIFFERENCES BETWEEN THE GFS (American) AND ECMWF (European) MODELS - Northern Hemisphere

MAXIMUM SKILL RANGE (WHEN MODELS ARE BETTER THAN CLIMATE NORMALS)

GFS: Days 1 to 8 (Summer and Fall) and Days 1 to 9 (Winter and Spring).
ECMWF: One more day than GFS.
Implication: GFS’s accuracy is similar to that of yesterday’s ECMWF model run.
Reason: ECMWF is run at higher resolution, with better observational data and statistical post-processing.
PATTERN SHIFTS

GFS does a good job of predicting pattern shifts 37% of the time.
ECMWF does a good job of predicting pattern shifts 61% of the time.
(“Good job” means anomaly correlation coefficient of 0.9 or better, skillful at synoptic changes.)
After 5 days, the GFS will tend to only detect large scale pattern shifts.
After 6 days, the GFS will tend to only detect the very largest scale global pattern shifts.
ECMWF is half a day ahead at catching synoptic pattern shifts and is more accurate.
WINTER WEATHER SKILL

1 Day Ahead: GFS is better
2 Days Ahead: Average of GFS and ECMWF is best
Days 3 and Beyond: ECMWF has higher skill
YEAR ROUND SKILL (IN GENERAL)

Days 1 to 5: GFS and ECMWF are comparable
Days 6 and on: ECMWF significantly higher skill (gap between the 2 models increases substantially)
SEASONALITY

Greatest model errors for GFS and ECMWF are in Winter, which are double the errors in Summer.
ECMWF is ~10% more accurate than GFS in Summer months and ~20% more accurate in Winter months.
MODEL QUIRKS

GFS

Once a month, GFS has “dropouts”, where the forecast is a major fail, a major outlier, and very divergent from the ECMWF, which does not have dropouts. GFS scientists are trying to fix dropouts through better initializations. One proposal is to use ECMWF initializations (better quality satellite observations), which would lower dropouts by 90%, but solutions are taking time.
Can run a cold bias in the Eastern U.S. (but OK in the West).
Ensembles can be over-confident (low ensemble spreads can still have low forecast accuracy).
Tends to have a warm bias in the upper troposphere.
Tends to have a cold bias for afternoon temperatures during warm months.
ECMWF

Tends to underestimate heavy precipitation events, but GFS has no such bias.
Tends to have greater model bias; GFS tends to have greater model absolute error.
Tends to have a cold bias in the stratosphere.
Tends to have a warm bias for morning temperatures.
DIFFERENCE BETWEEN GFS (OPERATIONAL) and GFS (ENSEMBLE)

GFS Operational is run at a higher resolution (more precision) than the GFS Ensemble. The GFS Ensemble uses as its “control” or “base run” a low resolution (watered-down) version of the GFS Operational run (to save on computing resources), then perturbs or varies this control “base run” slightly to produce the various members of the ensemble. As a result, sometimes the GFS Operational is different from the GFS Ensemble…and can even be more accurate at times. In general, use the ECMWF as an indicator as to whether to lean more heavily to the GFS Operational or the GFS Ensemble.

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Post by CPcantmeasuresnow Wed Mar 19, 2014 9:21 pm

Interesting read Mugs, thanks for finding that.
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Post by amugs Wed Mar 19, 2014 9:36 pm

@CPcantmeasuresnow wrote:Interesting read Mugs, thanks for finding that.
CP,
I thought so too and I actually sent an email to NWS about keeping score between the top four models global and short range models as well so we may actually have some sound factual, scientific information to base the extrapolated predictions on. Good stuff. Oh, I got no response so I'll try again and again can't hurt. Pereserverance usually wins out. 

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WINTER 2015-16 Total - 29.8" (Avg 35")
WINTER 2016-17 : 39.5" so far
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Post by NjWeatherGuy Wed Mar 19, 2014 9:47 pm

Interesting data, I've been doing some research on this too. I tend to find the GFS a decent model when compared to others and the only storm IMHO it completely blew this season was 2/13, other than that it's been ok generally actually did better than others in many storms. The NAM has been terrible, when taking the mean close to the storm it has the right idea but typically run to run is drastically different especially with QPF, one of the NAM/SREF main issues along with an overwhelming amped bias in the long range. CMC has a mid-long range amped bias and the EURO has a long range amped bias and a sometimes progressive bias. The GFS typically has a progressive bias if anything and sometimes underdoes QPF but I think it's mostly due to it being lower resolution. If they made the GFS resolution more like the EURO/CMC then IMHO it would be a very good model, I really do like the GFS and a lot of people knock it because it has its flaws. But I'd argue the EURO hasn't done much better.
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Post by amugs Wed Mar 19, 2014 10:09 pm

The GFS is going to become the poor child, the runt of the family without an upgrade and that is a fact seeing the euro and cmc will be operating at quantum speed and the gfs at dial up so to speak. 

All models overall where bad this winter, GFS did a better job with north systems/ vorts and euro did a good job with southern vorts. Cmc called a few and the srefs and nam hit a couple as well especially the Super Bowl mon storm.  

I am quite interested to see how far out in accuracy the cmc will be after its upgrades this spring.

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WINTER 2014-15 : 55.12" +.02 for 6 coatings (avg. 35")
WINTER 2015-16 Total - 29.8" (Avg 35")
WINTER 2016-17 : 39.5" so far
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