Canadian Forecast Models

[rogue]

Sorry to ask what is probably elementary to some. However, can anyone please explain the differences between the CMC, GGEM, and RGEM models? I know the RGEM only runs out to 48 hours while the GGEM runs out to 240 hours. But are they the same model and do the first 48 hours on the GGEM match the RGEM? Are they the same model but highlight different fields, or are they altogether different models? How does the CMC compare and contrast?  Have always been confused by the Canadian forecast models. Any info would be much appreciated. Thanks.

[Hoosier]

The CMC is not actually a model. It's the abbreviation for the organization that puts out the models.

The RGEM is a higher resolution than than the GGEM. The RGEM will often resemble the GGEM for the 48 hours but they're not the same. I'm sure a met could chime in with much more detail about the differences.

[rogue]

The CMC is not actually a model. It's the abbreviation for the organization that puts out the models.

The RGEM is a higher resolution than than the GGEM. The RGEM will often resemble the GGEM for the 48 hours but they're not the same. I'm sure a met could chime in with much more detail about the differences.

 

Appreciate the quick response. Yes, it seems that CMC (in terms of a model) and GGEM are often interchanged at different sources so I realize now that it's one and the same model. 

[JoMo]

Sorry to ask what is probably elementary to some. However, can anyone please explain the differences between the CMC, GGEM, and RGEM models? I know the RGEM only runs out to 48 hours while the GGEM runs out to 240 hours. But are they the same model and do the first 48 hours on the GGEM match the RGEM? Are they the same model but highlight different fields, or are they altogether different models? How does the CMC compare and contrast?  Have always been confused by the Canadian forecast models. Any info would be much appreciated. Thanks.

 

I think they've actually changed the name again.  Looks like the GGEM is now the GDPS and the RGEM is the RDPS. The RDPS grid is 10 km, while the GDPS is 25 km. I guess you could consider the RDPS the "NAM" and the GDPS the "GFS" in terms of American models. I think they have a hi-res version that's experimental (5km)  called the HRDPS.

[Rjay]

Love the gem-lam

[QcSevereWx]

http://meteocentre.com/models/models.php?mod=cmc_hrdps&map=na&run=〈=fr&mode=latest&yyyy=latest&mm=latest&dd=latest

[SnowGoose69]

Love the gem-lam

 

I just wish it was available over more areas.  Last I knew it was only over the NE U.S. and maybe Seattle or part of the Pac NW.  The RDPS had an amazing run in the winter of 13-14.  I did not find it was as good last winter though it was still better than many other models.  The RDPS biggest weakness is by far airmass convection, it badly overdoes coverage, in convection triggered by fronts or upper level features its much better.

[rogue]

I just wish it was available over more areas.  Last I knew it was only over the NE U.S. and maybe Seattle or part of the Pac NW.  The RDPS had an amazing run in the winter of 13-14.  I did not find it was as good last winter though it was still better than many other models.  The RDPS biggest weakness is by far airmass convection, it badly overdoes coverage, in convection triggered by fronts or upper level features its much better.

 

I remember how good it was during the winter of '13/'14 and then how disappointed I was last year with its performance. I would venture that it's perhaps attributable to certain synoptics being more favorable to read than others.  I know all about the adage that forecast models are only for guidance. But it's sobering to keep in mind that all the access to all the models and the myriad of data details and nice graphics mean absolutely squat when they get it wrong.

[Jim Marusak]

the RDPS is a lot better now at convection than it used to be before its revamping in order to take it to 4dvar. before the triggers were a mess and it was either feast or famine, and nothing in between. But as seen by the forecast leading up the the El Reno outbreak, they seem to have a much better combination now, getting storm mode much better. It helps for lake-effect convection as well.

 

As for the winter of 2013/2014, a lot of the models were a mess, not just the Canadian suite. Just think that winter should have humbled a lot of mets, and made them remember that models are only guidance, and not god. That being said, the GEM is usually excellent on p-types in the winter, and if you slide it into the right place spatially, you'd make some real good bets.

 

As for the canadian suite's tropical capabilities, it still has a horrible time handling the spin-up of tropical systems, as it seems like it wants to spin up every other tropical wave into a big system. But that being said, if it actually grabs the right system, track-wise its' actually not bad. Speed-wise, almost always seems to go way too fast, especially once it makes the turn. But in terms of catching tropical to extra-tropical transition, it doesn't do a bad job at all and should be paid attention (probably helps that researching the et transition is one of the big things they look at over the years).

 

as for the global run, it's not bad. not quite as good as the euro and probably on par with the gfs, percentage-wise. but the trend I usually see is the 4dvar-based models tend in one direction, the modified 3dvar ones go a different one, and the enKF ones tend to have their own direction.

 

at least that's my opinion of it from my usage, do others agree or disagree?

[Amped]

RGEM beats the NAM with wintry precip and is the only mesoscale model I would consider looking at for snowfall.