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1/23-24 Randytastic Snowstorm Part 2 STORM MODE THREAD

BxEngine

By BxEngine,
in New York City Metro

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WintersGrasp

WintersGrasp

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So, can any met or pro comment on why the NAM (which in many cases is a great short range model) was able to do a MUCH better job forecasting this storm at it's longest range out to 84 hours?? It clearly performed better than the euro and GFS, which are both made for long range forecasting. Now, I've always felt that the NAM was a model made for short range forecasts within 24-36 hours to point out where heavier precip may fall during a storm (though not necessarily the exact amounts because they are usually exaggerated). What was it about this storm/type of storm that fooled the other models, but not the NAM?

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billgwx

billgwx

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One reason could be because its higher resolution allowed it to capture the brick wall of mesoscale frontogenetic forcing required to produce such heavy snows in our area better than the global models. Funny thing was that it was right from the get-go if a little too far north.

 

A couple of days before the event I noticed it was a little farther north than the global models with the associated mid level low, and that for lack of a scientific description, it was doing something very weird with the intense mid level vort max progged to chug up the coast Friday night. These both may have lowered mid level heights enough in/near NYC to help open the floodgates. Still I was suspicious of this until Friday, and especially Friday night when the HRRR got within viewing range and modeled the intense banding that hit in the morning.

 

I remember reading Joe Bastardi's WxBell blog earlier in the week where he mentioned the NAM was the only model in his mind to capture the idea of the surface low tucking in closer to the Mid Atlantic coast. It has often done well with lows wrapping up in this area...once again better resolution of the low level thermal gradients between land and sea, also SST gradient north of the Gulf Stream?

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mikemost

mikemost

Posted
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One reason could be because its higher resolution allowed it to capture the brick wall of mesoscale frontogenetic forcing required to produce such heavy snows in our area better than the global models. Funny thing was that it was right from the get-go if a little too far north.

 

A couple of days before the event I noticed it was a little farther north than the global models with the associated mid level low, and that for lack of a scientific description, it was doing something very weird with the intense mid level vort max progged to chug up the coast Friday night. These both may have lowered mid level heights enough in/near NYC to help open the floodgates. Still I was suspicious of this until Friday, and especially Friday night when the HRRR got within viewing range and modeled the intense banding that hit in the morning.

 

I remember reading Joe Bastardi's WxBell blog earlier in the week where he mentioned the NAM was the only model in his mind to capture the idea of the surface low tucking in closer to the Mid Atlantic coast. It has often done well with lows wrapping up in this area...once again better resolution of the low level thermal gradients between land and sea, also SST gradient north of the Gulf Stream?

Thanks Bill. I was really looking forward to hearing some explanation of this.

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Morris

Morris

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One reason could be because its higher resolution allowed it to capture the brick wall of mesoscale frontogenetic forcing required to produce such heavy snows in our area better than the global models. Funny thing was that it was right from the get-go if a little too far north.

A couple of days before the event I noticed it was a little farther north than the global models with the associated mid level low, and that for lack of a scientific description, it was doing something very weird with the intense mid level vort max progged to chug up the coast Friday night. These both may have lowered mid level heights enough in/near NYC to help open the floodgates. Still I was suspicious of this until Friday, and especially Friday night when the HRRR got within viewing range and modeled the intense banding that hit in the morning.

I remember reading Joe Bastardi's WxBell blog earlier in the week where he mentioned the NAM was the only model in his mind to capture the idea of the surface low tucking in closer to the Mid Atlantic coast. It has often done well with lows wrapping up in this area...once again better resolution of the low level thermal gradients between land and sea, also SST gradient north of the Gulf Stream?

Thanks!

Isn't the para Euro as high in resolution as the 12km NAM?

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WintersGrasp

WintersGrasp

Posted
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One reason could be because its higher resolution allowed it to capture the brick wall of mesoscale frontogenetic forcing required to produce such heavy snows in our area better than the global models. Funny thing was that it was right from the get-go if a little too far north.

A couple of days before the event I noticed it was a little farther north than the global models with the associated mid level low, and that for lack of a scientific description, it was doing something very weird with the intense mid level vort max progged to chug up the coast Friday night. These both may have lowered mid level heights enough in/near NYC to help open the floodgates. Still I was suspicious of this until Friday, and especially Friday night when the HRRR got within viewing range and modeled the intense banding that hit in the morning.

I remember reading Joe Bastardi's WxBell blog earlier in the week where he mentioned the NAM was the only model in his mind to capture the idea of the surface low tucking in closer to the Mid Atlantic coast. It has often done well with lows wrapping up in this area...once again better resolution of the low level thermal gradients between land and sea, also SST gradient north of the Gulf Stream?

Thanks so much for taking the time to explain this. I guess I'll be taking the NAM seriously from now on. I know it was upgraded recently as well.

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Dark Star

Dark Star

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Thanks so much for taking the time to explain this. I guess I'll be taking the NAM seriously from now on. I know it was upgraded recently as well.

 

One reason could be because its higher resolution allowed it to capture the brick wall of mesoscale frontogenetic forcing required to produce such heavy snows in our area better than the global models. Funny thing was that it was right from the get-go if a little too far north.

 

A couple of days before the event I noticed it was a little farther north than the global models with the associated mid level low, and that for lack of a scientific description, it was doing something very weird with the intense mid level vort max progged to chug up the coast Friday night. These both may have lowered mid level heights enough in/near NYC to help open the floodgates. Still I was suspicious of this until Friday, and especially Friday night when the HRRR got within viewing range and modeled the intense banding that hit in the morning.

 

I remember reading Joe Bastardi's WxBell blog earlier in the week where he mentioned the NAM was the only model in his mind to capture the idea of the surface low tucking in closer to the Mid Atlantic coast. It has often done well with lows wrapping up in this area...once again better resolution of the low level thermal gradients between land and sea, also SST gradient north of the Gulf Stream?

Based on this explanation, the NAM progged the entire track of the storm better than the other models?  If so, I can put this to rest and put it in my files.  Thanks.

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ForestHillWx

ForestHillWx

Posted
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My question is why were the globals so inclined to chase the convection out in the Atlantic, as opposed to the more west based low pressure center? Was that a factor of the confluence it was picking up? Or were they more keyed in on the warmer SSTs and decided to redevelop the low at that location?

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