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March or BUST! - Pattern & Model Discussion


Baroclinic Zone

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10 minutes ago, wx2fish said:

NAMs picking up on it now, but we know how these can be

 

That upper low goes right over us so there could be some pretty steep lapse rates in that...def a norlun instability flavor to it. 

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16 hours ago, WthrJunkyME said:

If MPM is flying somewhere next week, lock it in.

 

 

11 hours ago, dryslot said:

At least this one is getting past 44N, That's a plus.

LOL to both.

Inasmuch as my travel has predicted better than the models of late.........

Keep an eye to next Monday/Tuesday when I might be in the Dakotas.  Beyond that, the time period between the 13-22 looks outstanding for epic snows as I might be back in SF.

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Just catching up.  Looks like there is a nice inv trough setup for Monday over the area.  Looks like we get some help with that ULL diving S to enhance the instability.  Sneaky potential on that.

Mid-week is still a great setup for the Forum as a whole.  Details to be ironed out but could be wet for some if it amplifies too much.  Antecedent air mass will be a marked improvement over yesterday so that's a plus.  

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38 minutes ago, moneypitmike said:

 

LOL to both.

Inasmuch as my travel has predicted better than the models of late.........

Keep an eye to next Monday/Tuesday when I might be in the Dakotas.  Beyond that, the time period between the 13-22 looks outstanding for epic snows as I might be back in SF.

Yay, winter continues!  I have hopes for this week anyway.

SF?  Don’t drop your keys.......

 

 

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1 hour ago, HoarfrostHubb said:

Yesterday’s storm was shuffling the furniture around...now it’s party time

We wanted to party with the vomit still everywhere from the night before but in the end we just needed to take a firehose (pun intended) to the place and clean it out....now it's time to party. We got a little pregame potentially Sunday night and then hopefully the main event Wednesday...potential round 2 next weekend as well. 

Kevin may have drank too many wine coolers and puked on the explorer, but time to get the coffee in him and get back on the horse for the next 10-15 days. 

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18 minutes ago, ORH_wxman said:

We wanted to party with the vomit still everywhere from the night before but in the end we just needed to take a firehose (pun intended) to the place and clean it out....now it's time to party. We got a little pregame potentially Sunday night and then hopefully the main event Wednesday...potential round 2 next weekend as well. 

Kevin may have drank too many wine coolers and puked on the explorer, but time to get the coffee in him and get back on the horse for the next 10-15 days. 

Hey I recognized before you yesterday we needed to mail it in

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It's interesting Scott...  There's clearly a tendency in the operational run types across the board to reflect a +PNA ... certainly at a minimum a +PNAP, whether the PNA is indeed positive or not in that time range.

To which, the PNA can be somewhat above(below) neutral SD while either a amplified or suppressed PNAP takes place.  For active weather over the U.S., particularly the eastern U.S. we obviously would prefer the amplified version. I.e., western ridge, eastern trough.

The reason the PNA and the PNAP can sometimes appear disconnected is simply because the PNA is YUGE!  ... 2/3rds of the thing can be say -.5 SD ... but that "forcing" also implies weak, and that allows the PNAP to evolve less perturbed. 

For those who have no idea what I'm talking about...

PNAP = Perennial North American Pattern   ... which features a slight bulge in the geopotential heights over the Rockies, with a flat counter-balancing trough over the east. So, an amplified PNAP means an exaggerated rest state of this dipole.  This is not an index so much as a recognized state of the field being biased one way or the other.  Thus a -PNAP is a western trough, eastern ridge...and so on. The Perennial nature of the PNAP is purely statistical average over many decades. However, it can be used as a quasi-index in the sense that if the rest state is +PNAP(-PNAP), then we can see a kind of "correction vector" ... such that when mapping systems through, they will tend to in part enhance(negate) respectively.

PNA = Pacific/North American ... and refers to the total characteristic of the flow type of a domain space that is almost the eastern half of Pacific Basin above the tropics, bounded in the east by much of North America.   Unlike the PNAP ... this is a standard index. It is calculated using an entirely different method in principle component analysis ... having to do with eigenvectors and ... basically at the end of which you end up with a polynomial, algebraic expression, that is thus solvable by completing the square/Quadratic to determine the roots.  The roots characterize the field... negative roots in the y coordinate are then averaged in the x, for two dimensional slices ... and if they balance negative or positive, the "character" of the field is established...

Now that you all have headaches...  my evil plan is almost complete -

Anyway, the PNAP is modeled to be amplified in the late middle and extended range ... if so, who knows how much.  I don't know what the EPS PNA has at this time, but the GEFS (which is carried by both CDC and CPC), is neutral-negative.  But again...that really means that the forcing from the Pacific is more likely weak one way or the other... which ..in effect, may be why the PNAP amplifies, because in the absence of said forcing, the torque budget from the westerlies over the western North America cordillera causes the ridge to formulate.  It's all really fascinating I know - :) 

Anyway, long of the short is that a +PNAP may also mean less SE ridging for one, but it also keeps hope alive for enthusiasts of cold storm types

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Actually ... edit/addendum... the CPC is indicating a modest +PNA out around D7-10, interestingly.  The CDC is the agency that's flagging it as sort of pallidly negative..

I should point out that although both do that Eigenvector calculation migraine gunk I briefly touched on... they do so for different atmospheric component analysis: CDC uses low level wind flux, therefore, anomalies there in; the CPC uses mid level geopotential heights in theirs.

I'm not sure if there is an advantage or not using either, relative to why they are also being used...  But for pattern recognition, it seems intuitive that the CPC may be more readily useful. The low level wind anomalies are ultimately going to be rooted in the same stuff though ... perhaps at minimum in the 80th percentile if not totally... so it's fine to use either.

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5 minutes ago, Typhoon Tip said:

Actually ... edit/addendum... the CPC is indicating a modest +PNA out around D7-10, interestingly.  The CDC is the agency that's flagging it as sort of pallidly negative..

I should point out that although both do that Eigenvector calculation migraine gunk I briefly touched on... they do so for different atmospheric component analysis: CDC uses low level wind flux, therefore, anomalies there in; the CPC uses mid level geopotential heights in theirs.

I'm not sure if there is an advantage or not using either, relative to why they are also being used...  But for pattern recognition, it seems intuitive that the CPC may be more readily useful. The low level wind anomalies are ultimately going to be rooted in the same stuff though ...

I'd just assume not endeavor to challenge the limitations of a decidedly negative PNA again.

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2 minutes ago, 40/70 Benchmark said:

Dude, my fiancé is going to call off the engagement......she almost killed me Thursday night when I took like 2 hours to write up that final call that went into the circular bin 20 hours later.

Imagine if this were 3 years ago. :lol:  

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