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Bust of the Century January 26-27 2015 model suites and discussions

Morris

By Morris,
in New York City Metro

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jm1220

jm1220

Posted
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NAM has been pretty much consistent with that same track though... 3 runs in a row. 

 

along with a slight eastward shift each run. 

 

can't just say 'throw it out' because it's what u want. 

There are solid reasons to throw it out. It's not wishcasting. Aloft, the storm looks even more favorable with the low closing off south of NYC. That should be more than enough to bring heavy snow into the city. 

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forkyfork

forkyfork

Posted
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The serious banding on the RGEM is further east. Considering that its last run was also far east (of the euro), we would have liked it to trend west, not the opposite. Hoping for the best with the euro, but expecting the worst. Kinda gets to a point where you can't toss out every other model....Or can you ? lol

looks like convective feedback problems with the two low centers

I_nw_r1_EST_2015012600_028.png

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forkyfork

forkyfork

Posted
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Does only the Euro know how to correctly handle convective feedback?

any model can have convective feedback... the issue is that these highly mesoscale models can take a small feature and run away with it. that's why they're only useful in the very short range
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WintersGrasp

WintersGrasp

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looks like convective feedback problems with the two low centers

 

What would cause so many of the models to have these convective feedback issues ? Originally, the NWS said that the euro had those issues (maybe because it was very favorable and a crazy solution?), but then seemed to back up on their thinking with that...

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The_Global_Warmer

The_Global_Warmer

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looks like convective feedback problems with the two low centers

 

 

 

Compared to 12z at 36 hours it's weaker and further East by quite a bit.  But there is some second weakening surface low pressure like 500 miles East.

 

Hard to tell on the B/W charts but it looks like it's less than 20MM for NYC which is around 0.75".

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jm1220

jm1220

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Yeah, I have a very hard time believing a low of that magnitude (captured no less) with such a spotty QPF output.

Models are going to have a very hard time resolving these things. It's a frequent problem with especially mesoscale models close into the event. But the deep convection robbing the main low is very infrequent in actuality. 

 

I remember even the day before the 12/19/09 storm and Boxing Day we had these issues. 

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Allsnow

Allsnow

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NAM has been pretty much consistent with that same track though... 3 runs in a row.

along with a slight eastward shift each run.

can't just say 'throw it out' because it's what u want.

How has the nam been consistent when it has shifted east the last three runs? This is the same model that had 14 inches for me 24 hrs out last sat

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phil882

phil882

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Looks like multiple lows on the Rgem to me like the NAM had. That can't be right can it?

A double barrel low is certainly possible... keep in mind the solutions both the NAM and RGEM are projecting were within the realm of possibilities provided by the ECMWF EPS.

This is more than just convective feedback... I've been looking at the initial conditions of the current clipper and it looks like its been moving a little faster than expected. For the best possible phase, we don't want this feature to be moving as quickly so the next shortwave can capture it further west and hence allow for surface cyclogenesis to occur further west. The trends aren't good because it looks like the last 12-18 hour forecasts were a bit too slow with the primary shortwave.

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SleetStormNJ

SleetStormNJ

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The RGEM took a step forward as far as its banding and precip signature over or near NYC this run without a doubt.  Also look at it for the overnight into tomorrow, it seems to be the only model catching onto the current radar trends.

 

It shows a pretty consistent batch of moderate to heavier snow over northern/NE/eastern NJ for a good period of time.  

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SleetStormNJ

SleetStormNJ

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A double barrel low is certainly possible... keep in mind the solutions both the NAM and RGEM are projecting were within the realm of possibilities provided by the ECMWF EPS. 

 

This is more than a convective feedback issue... I've been looking at the initial conditions of the current clipper and it looks like its been moving a little faster than expected. For the best possible phase, we don't want to be moving as quickly so the next shortwave can capture it further west and hence allow for surface cyclogenesis to occur further west. The trends aren't good because it looks like the last 12-18 hour forecasts was a bit too slow with the primary shortwave. 

 

Interesting.  Something to keep an eye through tomorrow.

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phil882

phil882

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The precip shield should be extending out further west though and there was a tidbit about that in the discussion earlier today. The Euro could be correct because it doesn't have any convective feedback and there's a better extension of the precip shield west given the closed lows and the look aloft. 

 

The Euro is still susceptible to convective feedback since it uses a cumulus parameterization (as do all models > 5 km). However, the ECMWF cumulus parameterization (Tidke scheme) is considered superior to the GFS (Simplified Arakawa Schubert) and NAM (Kain Fritsch) cumulus parameterizations.

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WintersGrasp

WintersGrasp

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A double barrel low is certainly possible... keep in mind the solutions both the NAM and RGEM are projecting were within the realm of possibilities provided by the ECMWF EPS. 

 

This is more than just convective feedback... I've been looking at the initial conditions of the current clipper and it looks like its been moving a little faster than expected. For the best possible phase, we don't want to be moving as quickly so the next shortwave can capture it further west and hence allow for surface cyclogenesis to occur further west. The trends aren't good because it looks like the last 12-18 hour forecasts was a bit too slow with the primary shortwave. 

Thanks for the info (that I wish it was not that bad!).....That would explain why we are getting the snow earlier over and also why the models are trending toward such a bad solution for us. At this rate, i'd be shocked if the GFS shows great solution, and especially if the euro continues its crush fest for us and doesn't move it much further east.....Seems like it could be turning into a 6-12" storm for NNJ/NYC, you think ?

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Nygmen

Nygmen

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Thanks for the info (that I wish it was not that bad!).....That would explain why we are getting the snow earlier over and also why the models are trending toward such a bad solution for us. At this rate, i'd be shocked if the GFS shows great solution, and especially if the euro continues its crush fest for us and doesn't move it much further east.....Seems like it could be turning into a 6-12" storm for NNJ/NYC, you think ?

TBF...it seems to be the other disturbance is slightly faster as well though...

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jm1220

jm1220

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Thanks for the info (that I wish it was not that bad!).....That would explain why we are getting the snow earlier over and also why the models are trending toward such a bad solution for us. At this rate, i'd be shocked if the GFS shows great solution, and especially if the euro continues its crush fest for us and doesn't move it much further east.....Seems like it could be turning into a 6-12" storm for NNJ/NYC, you think ?

I doubt the Euro would be this wrong so close in but I could see an east adjustment for sure. To me though the RGEM actually looked better than prior runs and the NAM seemed weird overall, which is common. Tonight if the Euro holds firm again it would be very hard for me to see the weaker/east camp being right. 

 

I'd say right now 80% chance NYC gets over 12", 50% chance at 18". 

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kevbo81

kevbo81

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I doubt the Euro would be this wrong so close in but I could see an east adjustment for sure. To me though the RGEM actually looked better than prior runs and the NAM seemed weird overall, which is common. Tonight if the Euro holds firm again it would be very hard for me to see the weaker/east camp being right. 

 

I'd say right now 80% chance NYC gets over 12", 50% chance at 18". 

 

agree jm

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Sophisticated Skeptic

Sophisticated Skeptic

Posted
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How has the nam been consistent when it has shifted east the last three runs? This is the same model that had 14 inches for me 24 hrs out last sat

 

 

The trends have been very minor shifts eastward.  It's overall structure has been the same and consistent the last 3 runs. 

 

If it was flip-flopping back and forth like crazy, then i'd throw it out myself.  But it's been solidly consistent it's last 3 runs.

 

I don't want the NAM to verify either, but usually when it's solid like this...it shouldn't be ignored. 

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