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April Discussion..Mild overall..and really not wild

Damage In Tolland

By Damage In Tolland,
in New England

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Typhoon Tip

Typhoon Tip

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Posted

Man ... where was this teleconnector prognostic outlook back in January!  With a rather statically albeit modestly positive PNA to offer up potential Pac impulses over N/A, while an NAO drills? Delicious kitchen aromas before the feast.

 

Buuut, for winter geese, you were pretty fortunate, nonetheless, for repetitive advent of those erstwhile -EPO intervals.  What a fantastic winter for EPO dominance, closing arguments on the debate over what domain space provides the primary cold loading pattern for N/A. 

 

Any questions, class?

 

-NAO, overrated?  To some degree, but not entirely ...  I always reflected upon the usage of the NAO as an over-popularization meme among the Met community, where some science/scientists pointed out it's significance in the 1990s during the mega winters; and then ... a lot of people latched on and ran with it, without really understanding what it means for us.  You can't just say, -NAO = cold and snow ... In fact, so ingrained was the resulting false assumption, these rows erupted metaphorically tantamount to religion heresy, if anyone dared to speak quantitatively/qualitatively outside the scope of the misconception. I, too, was a candidate for reproach in the early days. But I've learned through observation over the years, no.  If the AO is positive, and the EPO is positive, and the western NAO domain is negative, what exactly are you transporting?  

 

Most likely, cold that is generated over the Canadian shield -- which can perform reasonably well from late November on to about ~ March 31 .. and sometimes even as late as May (1977 exquisitely exemplified). However, cold masses of local origin, will not posses the same richness of that which is transported from Siberian and/or cross-arctic, which really requires some kind of neutral/negative EPO construct to take place.

 

I recall reading about the NAO in the 1980s, yet ... never heard it mentioned during the pre-internet era. I was an avid Weather Channel consumer, living vicariously through whatever they delivered, it was first "weather forum" available to us all.  They never mentioned it, either.  But when those big winters hit post Mt. Pinatubo

 AshCloud.jpg

 

There was a lot of apparent knee-jerk reactions and conclusions made about the why's and how's of those winter onslaughts.  

 

Now, .. we are in the last 1/3rd of April, and the EPO is positive, and the NAO is forecast to enter a phase of some extremeness in negative.  It's pretty interesting, for one, this did not take place ...ever, over the course of the winter. 

 

post-904-0-53074000-1398006791_thumb.jpg

 

I was dancing around a notion this morning that the -NAO "force" was probably always there, as perhaps argued by the multi-decadal NAO re-entering negative phase over the longer term curve; however, the -EPO and AA phase of the N. Pacific were just overwhelming. The result was R-wave spacing that muted the NAO to the point of flipping the phase into the anti-correlated positive mode much of the time.  But the real cause was always the Pacific.

 

It would be difficult to prove that without some form of advanced mathematics, that incorporates statistical/EOF calculations, after the application of a fluid/dynamic physical model that demos what takes place when removing the Pac forcing. ...

 

Anyway, the operational runs are now picking up the -NAO construct a bit more coherently for these last 10 days of the month.  What is [obviously] going to be less clear is what daily details will come of it.  The GGEM offers a D8 blue snow for the interior. The GFS as of the 06z comes real close to the same, while the Euro ... it shows the over-arcing ridge in the west based -NAO, but the wave length looks prematurely shortened (seasonally) such that we end up anti-correlated with enough M/A ridging to lock the cold N of SNE's latitude.   

 

None of these tools boast very good skill beyond 5 as we know, ...but this is going to be particularly true during a major modality in the teleconnects, taking place during one the more stachastic months of the year.  

 

I am still not ready to hang up the possibility for a snow until we get the NAO back on the positive recovery side. Despite all these 10 cent words, in the end ...it's just a feeling the weather could turn particularly antithetic relative to the hearts and desires of the summer geese. At last for a time.  The NAO overrated, yes... to some degree. But to many degrees, cannot be discounted. 

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weathafella

weathafella

Posted
Posted

So it's a fight to the finish re April temps. Looks pretty normal now through the end of the month with some sizable anomalies on each side. Should be interesting. I miss the 70s/80s. Friday was near 90 but I donned long sleeves for the long flight home. Mistake that was.

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