December Medium/Long Range Discussion

[dallen7908]

6 minutes ago, LP08 said:

It's my understanding that it only goes out to 90.

 

Edit: Ninja'd

A main purpose of the off hour Euro runs is to provide boundary and initial conditions for regional models used by member states. 

[flsch22]

10 minutes ago, psuhoffman said:

It only goes to 90

interesting. when did the euro start running at 0600 and 1800?  as reliable as the normal runs?

[dtk]

2 hours ago, pasnownut said:

actually check that.  Hi risk and i were discussing the other day and he said that it is too big an undertaking and they dont have the resources to convert the GEFS to Fv3.  I think you'll have a new Op to stare at w/ same old GEFS for longer range viewing.  I'll dig back through my posts and see if i can find it.  Need more coffee/dramamine first.

FV3-based GEFS will not be implemented until early FY 2020 (probably Q2...e.g. about Jan 2020).  Some of this is driven by human and compute resources as there is a requirement for a 30 year reforecast for calibration before implementation.

1 hour ago, dallen7908 said:

"Starting with the 00Z 19 December cycle, the FV3-GFS uses GFDL microphysics instead of the Zhao-Carr microphysics in the GFS."

Saw this in the information (i) section of the FV3-GFS comparison site.  Is this referring to 2018 or 2017?

 

Definitely 2017.  All official retrospectives and real-time experiment use the Lin-type GFDL MP scheme.

[clskinsfan]

This is going to be the once every hundred year screw job for our area. We have been screwed to the south plenty of times before. But it just doesnt happen in December. Although NOV was a top 5 cold for most of us as well. Who knows at this point. But I was worried about it being squashed late last week when I saw that ridiculous confluence to the north. In all honesty the models have really stuck with that theme for the past 4 days. Yes some runs relax it enough to get the precip up to us. But I am not really feeling great about this one. Hope I am wrong.

[osfan24]

4 minutes ago, clskinsfan said:

This is going to be the once every hundred year screw job for our area. We have been screwed to the south plenty of times before. But it just doesnt happen in December. Although NOV was a top 5 cold for most of us as well. Who knows at this point. But I was worried about it being squashed late last week when I saw that ridiculous confluence to the north. In all honesty the models have really stuck with that theme for the past 4 days. Yes some runs relax it enough to get the precip up to us. But I am not really feeling great about this one. Hope I am wrong.

The most consistent model so far with this storm is basically right where we all want it.

[WxUSAF]

@dtk tell us all why the superior physics and data assimilation techniques of the FV3 have locked in our snow here. Please? 

[usedtobe]

8 minutes ago, dtk said:

FV3-based GEFS will not be implemented until early FY 2020 (probably Q2...e.g. about Jan 2020).  Some of this is driven by human and compute resources as there is a requirement for a 30 year reforecast for calibration before implementation.

Definitely 2017.  All official retrospectives and real-time experiment use the Lin-type GFDL MP scheme.

Daryl,  How do the FV3 scores compare with the GFS?  Right now I use it as another ensemble member.  

[frd]

Right on time 

 

 

[usedtobe]

I wrote this on my Facebook page this morning.  I don't think any of the forecast problems outlined yesterday concerning the potential of a winter storm over the weekend have been resolved. The ensembles are not quite as bullish for snow as yesterday but there are enough members giving us moderate to heavy snow to not yet buy last night's (Monday night/early Tuesday morning) GFS and European runs which keep the bulk of the precip to our south. The parallel 06Z GFS still is a big hit and the Canadian model has the low tracking up the Chesapeake Bay introducing the possibility of rain. Those models and the heavier ensemble members argue to still keep all the options open ranging from the snow staying to our south to a significant (greater than 4" snowstorm) Besides, at these time ranges it's easy for the models to shift 100 miles north between now and Sunday.  My thoughts from last night's runs.  

[pasnownut]

20 minutes ago, dtk said:

FV3-based GEFS will not be implemented until early FY 2020 (probably Q2...e.g. about Jan 2020).  Some of this is driven by human and compute resources as there is a requirement for a 30 year reforecast for calibration before implementation.

Definitely 2017.  All official retrospectives and real-time experiment use the Lin-type GFDL MP scheme.

Thanks for the clarification.

 

[snowmagnet]

If we actually get this storm, is the timing now late Sunday into Monday? Also, I'm keeping track of the various models. What did the latest Ukie say?

[BaltimoreWxGuy]

6 minutes ago, snowmagnet said:

If we actually get this storm, is the timing now late Sunday into Monday? Also, I'm keeping track of the various models. What did the latest Ukie say?

Seems to be Sunday afternoon into early Monday. Something like that 

[LP08]

Well, the ICON is starting off 12z poorly.  Way south and barely any precip into va.  Including SW VA.  Good thing its just the ICON.

[cae]

I just took at look at FV3 bias scores... there still seems to be some room for improvement.  The below charts are for temps at 850 hPa and 1000 hPa (near sea level) over North America for the last month.  There's a similar bias for H5, but I'm not sure how meaningful that is.  The FV3 does well for H5 anomaly correlation, which I think is more important.

[dtk]

6 minutes ago, WxUSAF said:

@dtk tell us all why the superior physics and data assimilation techniques of the FV3 have locked in our snow here. Please? 

It's all part of our plan to get people to pay attention.  In reality, it is going to be dead wrong.

5 minutes ago, usedtobe said:

Daryl,  How do the FV3 scores compare with the GFS?  Right now I use it as another ensemble member.  

This is a pretty solid implementation, considering that we haven't had a chance to put a ton of new science into the package (outside of the model dynamics and MP scheme, a few DA enhancements, etc.).   For things like extratropical 500 hpa AC, it has gained us about a point (about what we'd expect/want from a biannual upgrade).  Improvements are statistically significant. 

I should caution, our model evaluation group has noted that there are times where the FV3-based GFS appears to be too progressive at longer ranges.  It's not clear how general this is and for what types of cases this has been noted.  

[psuhoffman]

2 minutes ago, LP08 said:

Well, the ICON is starting off 12z poorly.  Way south and barely any precip into va.  Including SW VA.  Good thing its just the ICON.

The flow is even more suppressive over the northeast. The last 48 hours that feature us fluctuating some but in general is not trending better 

[dtk]

2 minutes ago, cae said:

I just took at look at FV3 bias scores... there still seems to be some room for imrpovement.  The below charts are for temps at 850 hPa and 1000 hPa (near sea level) over North America for the last month.  There's a similar bias for H5, but I'm not sure how meaningful that is.  The FV3 does well for H5 anomaly correlation, which I think is more important.

Yes, the cool/low height bias with increasing forecast time is already well known and documented.  In fact, I am pretty sure there is already a fix for this particular issue, though it is too late to include in the Jan. 2019 implementation.

[nj2va]

9 minutes ago, LP08 said:

Well, the ICON is starting off 12z poorly.  Way south and barely any precip into va.  Including SW VA.  Good thing its just the ICON.

It wasn't even close either.  Hopefully the GFS doesn't head in the same direction.

[psuhoffman]

Since no one else will do it I will. The nam at 84 is significantly more amplified with the stj and less suppressive with the NS then even the 6z Fv3. It's the nam at 84 so...but if we're gonna bring up the icon might as well mention it.  

[LP08]

Just now, nj2va said:

It wasn't even close either.  Hopefully the GFS doesn't head in the same direction.

Really suppressive over the NE.  Through 39 on the GFS, all I notice so far is that it is slower compared to 6z.

[psuhoffman]

Just now, nj2va said:

It wasn't even close either.  Hopefully the GFS doesn't head in the same direction.

It tries for a late capture and tug North but not enough. Thats a feature on a few runs now. Maybe it trends towards a frintrunner wave that escapes and a secondary that comes up.  Doubtful though. Our big problem is the NS vorts diving through New England right in front and so far those features remain. 

[Ji]

1 minute ago, psuhoffman said:

Since no one else will do it I will. The nam at 84 is significantly more amplified with the stj and less suppressive with the NS then even the 6z Fv3. It's the nam at 84 so...but if we're gonna bring up the icon might as well mention it.  

ICON seems like its really on its own alot of times...sometimes good for weenies and then you have today. It dosent seem like a good model

[psuhoffman]

Just now, Ji said:

ICON seems like its really on its own alot of times...sometimes good for weenies and then you have today. It dosent seem like a good model

It's really going to come down to that flow to our northeast. If that relaxes there is nothing stopping this. But if that remains a wall with vorts littlerally diving through Boston as the storm is trying to turn the corner it's going to stay south. 

[psuhoffman]

One of the reasons I keep thinking "keep it close" is I do think once this gets going with all that heat influx from a juiced up stj it will likely pump some ridging in front more than guidance is catching at range. So if we can get to the closing stages close...with a central VA target...needing a 50-100 mile adjustment we could be ok. If we go into the endgame looking at a NC bullseye then it's probably too much to ask. 

[Ji]

gfs does not look more suppressed so far than 6z lol...

[yoda]

GFS looks okay I think through 78... I think

[Ji]

4 minutes ago, psuhoffman said:

One of the reasons I keep thinking "keep it close" is I do think once this gets going with all that heat influx from a juiced up stj it will likely pump some ridging in front more than guidance is catching at range. So if we can get to the closing stages close...with a central VA target...needing a 50-100 mile adjustment we could be ok. If we go into the endgame looking at a NC bullseye then it's probably too much to ask. 

dude---everytime we have needed a north trend in the past couple of years to get snow...we have have failed. the north trend only happens when we dont need it to

[mappy]

2 minutes ago, yoda said:

GFS looks okay I think through 78... I think

why not just let it run and see what happens? 

[Snowchaser]

CMC looks pretty good so far

[nj2va]

Through 78, heights are a little lower on the EC vs 6z but that may be due to the fact that the NS vort is a little faster this run.  Maybe it'll get out just in time to allow this to come north.  We'll see...