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Model Mayhem VII

Typhoon Tip

By Typhoon Tip,
in New England

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CoastalWx

CoastalWx

Posted
Posted

My statement was independent of next weekend. That's said, I don't buy the whole it trends warmer this time of year. We have had many events over the last few years that have trended the other way in March as well. It's usually rather hostile for snow this time of year....especially in lower elevations. It only takes a fart from a Pelican on the pier at Clearwater Beach to trend something "warmer." In other words, it's already tough to get snow. 

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Ginx snewx

Ginx snewx

Posted
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24 minutes ago, CoastalWx said:

My statement was independent of next weekend. That's said, I don't buy the whole it trends warmer this time of year. We have had many events over the last few years that have trended the other way in March as well. It's usually rather hostile for snow this time of year....especially in lower elevations. It only takes a fart from a Pelican on the pier at Clearwater Beach to trend something "warmer." In other words, it's already tough to get snow. 

Models overdo lower level cold in SNE in late March and April more often than not. Doesn't mean it can't snow as we saw last April, does mean be careful with verbatim marginal air masses.

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dendrite

dendrite

Posted
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1 hour ago, Ginx snewx said:

Keep a keen eye on it. Watch it closely, might make its own cold. GFS looks great, have to give it to the GFS......FYI it's not a cutoff, have no idea where that came from 

The GFS is tossed further than a Chuck Knoblauch throw to 1st base.

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CoastalWx

CoastalWx

Posted
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42 minutes ago, Ginx snewx said:

Models overdo lower level cold in SNE in late March and April more often than not. Doesn't mean it can't snow as we saw last April, does mean be careful with verbatim marginal air masses.

All that matters is track and temps just off the deck. I don't see a notable reason why guidance 5 or 6 days out will always trend warmer. 

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dendrite

dendrite

Posted
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8 minutes ago, Ginx snewx said:

Sarcasm missed. I was at Yankee Stadium behind first base when Knoblauch nailed Olbermanns old lady in the head.

Nah...I knew it was sarcasm. Just throwing it out there. The GFS has done some funky things with overdoing the lowlevel cold at times the past couple months. 

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CoastalWx

CoastalWx

Posted
Posted
28 minutes ago, dendrite said:

Nah...I knew it was sarcasm. Just throwing it out there. The GFS has done some funky things with overdoing the lowlevel cold at times the past couple months. 

The euro too. It's been way too cold with the snow cover. At least down here. 

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Typhoon Tip

Typhoon Tip

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I think the issue with the 'models trend warmer vs colder' thing has to do with:

 a   ... the transition seasons more so, and I always thought it was more an issue in MOS (machine) products. I (and others) have suspect that the MOS products are prone to increased error in autumn and springs (and this is common in the vernacular from NWS offices to NCEP head-quarters in back enough to conclude this consensus) - but,

 b   ... I have not read or heard of that error being quantified or qualified in Global numerical models, no - MOS, yes.

That doesn't mean to say there isn't notable error from the Globals, just that it would be news to me. And common practice doesn't reveal anything as dramatic as that which can be readily quantified in the MOS's.  

I coded a kind of MOS product while as an undergrad at UML that was based off the FOUS gridded data.  I developed FORTRAN algorithms that employed Poison's Equation (along with other stuff) for determining diurnal surface temperatures at intervals and ranges. I used to get bigger errors while testing during spring and autumn; until I invented a kind of "cheat".

I realized the errors were bigger in sunny times in spring, and cloudy stormy times in autumn. That naturally led me to conclude that just using the raw FOUS grid wasn't accounting for that super adiabatic mixing layer at the very bottom, or... it was not seeing inversion in CAA in falls... etc.  

So, I created a coefficient that I derived by taking June 21 and December 21, ...In that paradigm, I assumed a linear loss or gain going forward from those resptective dates. This was a sloppy way of accounting for the bottom of the Ekman mixing layer. In reality, that sun's power is a sinusoidal curve across the year, but for the purpose of the algorithms the linearity was a close enough approximation. 

In any case, if people use the MOS' flat values on sunny days in early April, ...when there aren't any counter-balancing/offsetting forces at work, chances are your numbers will bias slightly cool. ...sometimes more than slightly.  And vice versus October and November. 

However, I don't know if that applies to the Euro or GFS' thickness tapestries.  

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dendrite

dendrite

Posted
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MOS has a growing brain of statistical data. I'm not sure which model height levels are factored into the output. With the abundance of vertical levels you would think it would/should include a good representation of the low levels now...i.e. 950, 925, 900, 875, 850. If it's just outputting 2m temps via statistical data of nothing between the sfc and H85 it's probably going to struggle to sniff out the low level CAD or superadiabatic potential. The superadiabatic potential is going to be difficult to sniff out regardless...especially with an earlier than normal pack melt/mud season. If the database is loaded with mostly snow cover days in March it's obiously going to overestimate the albedo in torchy March days with no pack or mud. Just look at 2010 and 2012 to see those busts. The MET tends to do better with CAD versus the MAV so maybe it has more low levels factored in. The models and parameters seem to constantly be changing these days so it's hard to keep track with which model does what.

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Cold Miser

Cold Miser

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Posted
Just now, dryslot said:

Translated, The GFS is garbage and don't know why anyone even uses it to forecast.

lol. 
True enough.  But even seeing a sliver of hope regardless of how crappy the chances are helps as I rock back and forth, and stare blankly out the window, watching the snow erode away as drizzle falls from above.  

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dryslot

dryslot

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7 minutes ago, Cold Miser said:

lol. 
True enough.  But even seeing a sliver of hope regardless of how crappy the chances are helps as I rock back and forth, and stare blankly out the window, watching the snow erode away as drizzle falls from above.  

lol, Its true though, Getting to the time of year where the winter threats are waning, Big differences between the GFS and Euro, Euro keeps it wintry over NNE whereas the GFS keeps it south over SNE next weekend

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ORH_wxman

ORH_wxman

Posted
Posted
1 minute ago, CoastalWx said:

That's a bizarre H7 and H5 look though. I would rather something more concise. It's rather disorganized at that level...but sort of meaningless to get picky.

Almost looks like this guy:

http://mp1.met.psu.edu/~fxg1/NARR/1993/us0324.php

 

Horrible forecast bust that day. I think mostly rain turned into 8-10 inches of paste for Boston.

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