Model Mayhem VII

[40/70 Benchmark]

21 minutes ago, ORH_wxman said:

https://www.americanwx.com/bb/topic/49832-the-blizzard-of-the-ides-2017-observation-time/?do=findComment&comment=4526148

 

I made a couple posts starting there, the next one was on the next page I believe.

 

The models seemed to struggle with the convection in this past storm. There was a lot of it...like tons of it actually. Way more than usual. I always hate trying to pick models when there's an anomalous amount of convection because sometimes it is hard to parse between reality and convective fantasy on the models. I do think you have to weight the non-hydrostatic models a little more than usual in those storms. I think the RGEM being really far west was a definite flag...esp when it didn't come eastward once it got to like 30-36 hours...it kept going west actually until it finally overtrended a smidge (took low over BOS) and then ticked back slightly east to near the final track just SE of BOS-PVD line. RGEM doesn't have a huge bias of over-amping storms like the NAM or even the Ukie sometimes does...and the Ukie had a very west track too. So to me, the RGEM was pretty key. Some of those models were a little too warm up this way...not much mixing ever happened beyond 128 and N of pike...but everything else was pretty accurate. They actually might not have been warm enough down near NYC where the warm tongue was really strong.

 

The convection is why s streamers often trend west, and why I kept feeling uncomfortable while many were doing blizzard dances.

[Gibbsfreeenergy]

10 minutes ago, CT Rain said:

NCAR ensemble did OK but was still too high on the southern flank with snow totals.

Biggest issue I believe was the fact our SLR were so abysmal... super dense/small snowfalkes with a dried out SGZ. 6.4:1 here in my backyard. Man snow. 

Ryan and I have had some talk over txt msg about this

my quick thoughts can be basically summarized as ...some synoptic scale errors (Mid Level low) tracking farther west than majority of models, and this led to 2 main issues 1) poor SLR that Ryan mentioned (around a 30th percentile of the distribution of a 7-1, where 50th percentile is 10-1. Worth noting that a 1 stdev SLR is around 6, so think about that over a 2in QPF bomb). Most of the error from the RH/DGZ/omega poor juxtaposition...  and 2) of course the stronger warm layer in 850-725 layer for southern areas, also a byproduct of ML low positioning.      but I would add a third    3) and a 4)..... 3) Knowing when to say screw you models based on historical synoptic scale features that say be cautious in forecasting high end snow totals   and 4) knowing when to change forecast and abandon ship, and admit bust. It is suprising to me how many have issues admitting bust. But I guess you get used to it after a while so it becomes easier with time/age lol 

[Gibbsfreeenergy]

4 minutes ago, Gibbsfreeenergy said:

Ryan and I have had some talk over txt msg about this

my quick thoughts can be basically summarized as ...some synoptic scale errors (Mid Level low) tracking farther west than majority of models, and this led to 2 main issues 1) poor SLR that Ryan mentioned (around a 30th percentile of the distribution of a 7-1, where 50th percentile is 10-1. Worth noting that a 1 stdev SLR is around 6, so think about that over a 2in QPF bomb). Most of the error from the RH/DGZ/omega poor juxtaposition...  and 2) of course the stronger warm layer in 850-725 layer for southern areas, also a byproduct of ML low positioning.      but I would add a third    3) and a 4)..... 3) Knowing when to say screw you models based on historical synoptic scale features that say be cautious in forecasting high end snow totals   and 4) knowing when to change forecast and abandon ship, and admit bust. It is suprising to me how many have issues admitting bust. But I guess you get used to it after a while so it becomes easier with time/age lol 

 

[CT Rain]

I also think the big heat the NWS is getting is partially based on their statement on the bust... which was effectively, "we thought the storm would be less but we didn't want to tell people in case they wouldn't take it seriously." 

That's ridiculous. I can't imagine being confident a forecast is too high and just say... wth let me just let it ride.

I do think that one problems humans have with forecasts is that we tend to ignore some computer guidance when it goes against group think (board and social media) and some kind of cognitive dissonance. We need to be careful about this because we're not too far off from having machines making these decisions for us - clealry the raw model blends and the raw WPC guidance was better than what the WFOs came up with. 

One thing we try to do on the broadcast side is to stay consistent and avoid a windshield wiper kind of forecast... and sometimes I think we do this to a fault. Going back and looking at some of the model data for NYC and coastal CT is that there was a clear signal for mixing issues as early as the 00z run ealry Monday AM. 

[Gibbsfreeenergy]

2 minutes ago, Gibbsfreeenergy said:

 

http://journals.ametsoc.org/doi/pdf/10.1175/WAF856.1

 

Table 2

[CoastalWx]

GEFS are rather wet.

[Ginx snewx]

2 hours ago, RUNNAWAYICEBERG said:

Surprised Ginxy comes in with a snow map to put up a stance on the snowy solution, I expect more from him.

This is for east of 91 and south of BOS. If you are there, congrats on an advisory type or maybe you can pull out a 6" weenie if shes good enough. west have to hope for magic and vodoo. 

Keep up. They were pig piling on James because a terrible TT map showed CC blank

[ORH_wxman]

I posted this in the model thread before the storm:

 

 

The models are not entirely trustworthy when you have 2" of QPF in a WCB...I know some spots did verify 2" of qpf esp down in CT, but overwhelmingly, at least up here in MA, it did not. Most of the precip totals were in the 1.25-1.70 range looking at cochorahs....so it's no surprise that we didn't get 18"+ snowfall amounts. CT had the mixing issues though that posed problems during a larger portion of the heavy QPF...Ryan alluded to. Prob why ratios were 7 to 1.

[CoastalWx]

Randolph did have nearly 2" QPF. It was close, but the ratios of 6-7:1 were definitely in the uncommon category.

[CoastalWx]

Pope Bene working some GEFS magic hopefully.

[Ginx snewx]

37 minutes ago, CT Rain said:

NCAR ensemble did OK but was still too high on the southern flank with snow totals.

Biggest issue I believe was the fact our SLR were so abysmal... super dense/small snowfalkes with a dried out SGZ. 6.4:1 here in my backyard. Man snow. 

I thought the Euro Ptype maps were pretty damn good. Seems qpf was correct after all. 

[ORH_wxman]

Just now, Ginx snewx said:

I thought the Euro Ptype maps were pretty damn good. Seems qpf was correct after all. 

QPF was too high up here....very few amounts over 1.70". Slicing about 25-30% off QPF forecasts was probably the best move. Ironically, the GFS was the closest to QPF in this area of SNE...but it had a track that was too far east, so its QPF amounts were probably horrible out west, esp in NY State.

[RUNNAWAYICEBERG]

4 minutes ago, Ginx snewx said:

Keep up. They were pig piling on James because a terrible TT map showed CC blank

I am slow, you know this from all the hardcore abuse of meth crack and heroin I am apparently never going to recover from. My bad. Thought you were referring to a widespread sne snowstorm and not just what it showed for CC MA USA EARTH.  

[CT Rain]

4 minutes ago, ORH_wxman said:

I posted this in the model thread before the storm:

 

 

The models are not entirely trustworthy when you have 2" of QPF in a WCB...I know some spots did verify 2" of qpf esp down in CT, but overwhelmingly, at least up here in MA, it did not. Most of the precip totals were in the 1.25-1.70 range looking at cochorahs....so it's no surprise that we didn't get 18"+ snowfall amounts. CT had the mixing issues though that posed problems during a larger portion of the heavy QPF...Ryan alluded to. Prob why ratios were 7 to 1.

We had surprisingly little mixing here - some sleet for sure - but I was 6.4:1 of mainly snow. It was exceptionally dense with hideous hideous snow growth. If you look at some of our soundings we were completely dried out colder than -9C in the column or so for a good part of the event. 

But yeah I think your point is a good one... we frequently overdo the WCB QPF. 

When the H7/H5 low goes so far west there are all sorts of issues... including RH problems to contend with. 

[Ginx snewx]

1 minute ago, ORH_wxman said:

QPF was too high up here....very few amounts over 1.70". Slicing about 25-30% off QPF forecasts was probably the best move. Ironically, the GFS was the closest to QPF in this area of SNE...but it had a track that was too far east, so its QPF amounts were probably horrible out west, esp in NY State.

NE Mass was overdone but looking at Cocorahs 2 days totals it wasn't terrible. Look back at the 0Z Euro Ptype maps, not bad

[jbenedet]

3 minutes ago, CoastalWx said:

Pope Bene working some GEFS magic hopefully.

That's a great look for SE sections, particularly with a few members skewing the mean southeast.

I do a lot of magic apparently...

 

[Juliancolton]

1 minute ago, ORH_wxman said:

The models are not entirely trustworthy when you have 2" of QPF in a WCB...I know some spots did verify 2" of qpf esp down in CT, but overwhelmingly, at least up here in MA, it did not. Most of the precip totals were in the 1.25-1.70 range looking at cochorahs....so it's no surprise that we didn't get 18"+ snowfall amounts. CT had the mixing issues though that posed problems during a larger portion of the heavy QPF...Ryan alluded to. Prob why ratios were 7 to 1.

I had 2.52" of liquid, which was in line with the wettest models or even slightly higher. There were even a few 3"+ reports east of the Hudson... I think the only global with QPF that high was the UK, but I may be wrong. Never deviated from pure snow, so it was 6.7:1 sand. I expected ratios to be a little below climo based on the wind and warm low-mid level temps, but it's pretty exceptional to only get 17-20" of snow from 2.5"-3" of liquid.

[Ginx snewx]

1 minute ago, CT Rain said:

We had surprisingly little mixing here - some sleet for sure - but I was 6.4:1 of mainly snow. It was exceptionally dense with hideous hideous snow growth. If you look at some of our soundings we were completely dried out colder than -9C in the column or so for a good part of the event. 

But yeah I think your point is a good one... we frequently overdo the WCB QPF. 

When the H7/H5 low goes so far west there are all sorts of issues... including RH problems to contend with. 

Yet not too far from you in NWCT the WCB 2 footer amounts happened.  What was the difference?

[WinterWolf]

1 minute ago, CT Rain said:

We had surprisingly little mixing here - some sleet for sure - but I was 6.4:1 of mainly snow. It was exceptionally dense with hideous hideous snow growth. If you look at some of our soundings we were completely dried out colder than -9C in the column or so for a good part of the event. 

But yeah I think your point is a good one... we frequently overdo the WCB QPF. 

When the H7/H5 low goes so far west there are all sorts of issues... including RH problems to contend with. 

Hey Ryan,  I remember some RH maps being posted, and CT was all in the 98,99,100% category.  Were those all wrong??  

 

I had about 45 minutes of sleet here in Southington, then it went back to snow.  After about 11:00 am the snowgrowth got much better here and it went to town.  Ended up with 14 inches.  

[RUNNAWAYICEBERG]

4 minutes ago, CoastalWx said:

Pope Bene working some GEFS magic hopefully.

The Pope is not a magician, he is an extension of reality from thousands of years ago.

 

2 minutes ago, CT Rain said:

We had surprisingly little mixing here - some sleet for sure - but I was 6.4:1 of mainly snow. It was exceptionally dense with hideous hideous snow growth. If you look at some of our soundings we were completely dried out colder than -9C in the column or so for a good part of the event. 

But yeah I think your point is a good one... we frequently overdo the WCB QPF. 

When the H7/H5 low goes so far west there are all sorts of issues... including RH problems to contend with. 

 We had great snow growth out here to start, i mean 4-5" per will do that, but once the mega band shredded and the best stuff lifted nw, it sucked and along came the sleet to boot. 

WeatherWeezy (Paul) did very well imo, he was waving the red flags with authority very early but only a select few listened. 

[Ginx snewx]

There were flags in the Euro which were discounted 

[ORH_wxman]

4 minutes ago, Ginx snewx said:

NE Mass was overdone but looking at Cocorahs 2 days totals it wasn't terrible. Look back at the 0Z Euro Ptype maps, not bad

They were overdone across most of MA...exception might have been the Berkshires...and a few scattered areas in SE MA got 2"....but out of 112 cocorahs reports in MA, only 11 exceeded 2 inches and only 27 exceeded 1.70 inches...so it was overdone.

 

It seems there were two camps of issues on the totals...one was overdone QPF...which applied to further north in MA....the other was SGZ drying out too quickly and/or some mixing issues in CT where QPF was higher.

[RUNNAWAYICEBERG]

5 minutes ago, Ginx snewx said:

There were flags in the Euro which were discounted 

Dood, I didnt realize how close I was to 20+ aaaaaaaah. 

[WinterWolf]

1 minute ago, RUNNAWAYICEBERG said:

Dood, I didnt realize how close I was to 20+ aaaaaaaah. 

Berg, what did you end up with from the Tuesday Storm?

[jbenedet]

47 minutes ago, CT Rain said:

I also think the big heat the NWS is getting is partially based on their statement on the bust... which was effectively, "we thought the storm would be less but we didn't want to tell people in case they wouldn't take it seriously." 

That's ridiculous. I can't imagine being confident a forecast is too high and just say... wth let me just let it ride.

I do think that one problems humans have with forecasts is that we tend to ignore some computer guidance when it goes against group think (board and social media) and some kind of cognitive dissonance. We need to be careful about this because we're not too far off from having machines making these decisions for us - clealry the raw model blends and the raw WPC guidance was better than what the WFOs came up with. 

One thing we try to do on the broadcast side is to stay consistent and avoid a windshield wiper kind of forecast... and sometimes I think we do this to a fault. Going back and looking at some of the model data for NYC and coastal CT is that there was a clear signal for mixing issues as early as the 00z run ealry Monday AM. 

Great post. Regarding group think I believe the worst trap gets set when guidance and group (forecaster) consensus are aligned inside 48 hrs. You, the individual may be incredulous -- but do you have enough to go against the herd (model consensus + forecaster consensus)? 

Another issue is overestimating the power of ensemble forecasts. How many times do we see a final solution that was outside the envelope of solutions inside 48 hr...All too often.

[correnjim1]

9 minutes ago, Ginx snewx said:

There were flags in the Euro which were discounted 

is that for this weekends system? it looks like a map from Tuesdays storm.

[RUNNAWAYICEBERG]

9 minutes ago, WinterWolf said:

Berg, what did you end up with from the Tuesday Storm?

14", that map confirms it too. 

[CTWeatherFreak]

6 minutes ago, correnjim1 said:

is that for this weekends system? it looks like a map from Tuesdays storm.

LOL... What makes you think it isnt?

[RUNNAWAYICEBERG]

6 minutes ago, correnjim1 said:

is that for this weekends system? it looks like a map from Tuesdays storm.

Yes, this weekends ull magic show will partial triple phase PFs nuts again with a 40 burger. 

[Ginx snewx]

9 minutes ago, correnjim1 said:

is that for this weekends system? it looks like a map from Tuesdays storm.

Post analysis of Tuesday