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Tracking Jan 7 coastal storm. Lingering compression/flow velocity has not lent to consensus, but it seems at 30 hours out.. finally?


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2 minutes ago, IowaStorm05 said:

I’m not optimistic about this thing at all.

especially after falling for the GFS, which refuses to factor in the presence of very dry air. They tried to tell me.
 

I should probably check back on Wednesday night. 

 

You'd have loved the NGM.  The NGM would regularly throw back major snows into air that could not support someone's breath

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1 hour ago, tavwtby said:

I wanted an explanation on the GFS op v ensemble v mean, is the op run the most reliable, are there certain algorithms or parameters in common that make it the op, or is it simply the initial run and the other members are spit out in order, that's what I never knew and thought someone could explain... relevant to this signal, the GFS op is basically ots with the 7th, but has many members near the BM, so hence my curiosity.

Oh ... I see.  yeah - good questions.

The operational version is a "souped up" ensemble member ...It has incorporated the best theoretical application of Meteorological physical equations -it's called the 'operational version'.   Most reliance is there.

The ensemble means have less integrated total tech manifolds, and/or employ more 'experimental' physical equations.  They are thus considered, 'perturbed' version members.  Individually, they are less likely to best the operational model ...particularly in shorter duration lead ( < 72 hours)... where as, the extended complete mean ( all members/ n-terms), offers stability - a kind of normalization that the operational falls victim due to chaos feed-backs cumulatively effecting accuracy way out in time. 

That's sometimes why you might hear[ responsible minded ] contributors ( lol ) refer to relying upon the ensemble mean in the extended, which by convention is anything out side of 5 days ...Relative to the pattern at hand, sometimes that is shorter or longer by a day in either direction.  I've seen patterns where operational versions nail things down pretty tight on D6 .. but I've also seen operational version have trouble as close as D3. The respective ensemble means tend to perform better in lesser confidence circumstances.

The last 5 years -worth of winters (imho ...) have not been particularly good operational version years ... probably owing to the compressed, fast flows.  Models don't tend to do as well in long X-coordinate, short Y coordinate flow types, which seems to be dominating the winter hemispheres as of late. 

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ooops, posted this in the wrong thread

 

WPC day 4 map looks perfect, with the low forming right in the Delaware Bay and 24 hours later  NNE of NS.  That is a good track for interior SNE, CNE, NNE.  And from the discussion:

Regarding the early period East Coast low, the 06z/12z
GFS continues to be faster/more offshore with the track while the
bulk of the rest of the guidance suggests something closer to the
coast and a more impactful winter storm from the lower Ohio Valley
into the Northeast.

And in the threats/hazards everywhere form just nw of Philly into all of NE is under threat for heavy snow.  

I'm thinking a general 6-12 is coming.

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16 minutes ago, SnowGoose69 said:

You'd have loved the NGM.  The NGM would regularly throw back major snows into air that could not support someone's breath

The Nested Grid Model? That’s a throwback even older than the “Lean Back” song. A feature of my teenage years reading what were much more jumbled forecast discussions at the NWS. I consider 2006-2016 even to be fairly modern with forecasting accuracy but the late 1990s thru perhaps 2002 were messy and full of many weird surprises.

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