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January 2024 -- Discussion


moneypitmike
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14 minutes ago, CoastalWx said:

Just looking at the euro, but the problem I see is that the ridge out west later this week is not high amplitude and is transient. That may limit how far that trough can dig and is the reason for these offshore looks. But, it’s not far off from a biggie for sure 

Hopefully that changes and the models are underestimating the amplitude of the ridge.

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Scott nailed it in his morning/brief analysis, using the Euro to describe primary limiting factors re the 20th system - it's actually consistent as an observation across all guidance, really.  It's also been the case since the period in question first began to emerge in the operational versions.  ..some 3 or 4 days going back  (btw, the 20th was suggested via other means going back long prior to the operational model detection - ), and has persisted ever since.

Just want to add some analysis/observations to that.  From a broader perspective, the velocity of the field is there first, and is "why" the above factor has persisted.  

Why?  The models have difficulty (perhaps a range -related thing .. I wonder ) constructing N-S orientations - it becomes a geometric problem in that higher velocity, when going around any curvilinear trajectory, induces an outward acceleration force that is normal ( perpendicular ) to the surface at every point around the curve.  This acceleration force is centrifugal, or "g-force" as is often referred. As the speed of the movement around the curve increases, the g-force increases with it. 

How it effects the geometry the atmospheric circulation pattern:  When the effect is large, it's because thermal wind vector component of the geostrophic wind equation is very large in higher gradient, and caused higher wind; that forces the curve to open up.  One needs to compare equations ( mathematically ) to assist in proving this, but the aforementioned concept matches the observation in the field rather nicely.

It's fascinating if one understands this.  

Annoying and invoking of chiding when they don't.  

I understand this... buuuut, unfortunately, the fascinating aspect is being on textbook display and is why this isn't already modeled as a 1978 redux. 

All the players are initially present.  In fact, even the super synoptic indicators are flagging something incredible.  The idiosyncrasies surrounding the negative interference via too much flow velocity, that is unfortunately not described very well in either the snap shot of identifiable features, nor these numerical teleconnector projections, respectively. 

1     The PNA is rising slowly anyway nearing the period, but, all sources 'jolt' the index from ~ -1.0 to +1.0 SD in the 2 days immediately antecedent. That's a big signal from a super synoptic source  - check

2    The -NAO corrects to neutral - this is physically expressed on the synoptic charts as the western end of the block collapsing S across the Canadian Shield; underneath this mode change, the 'SPV fragment and cold mid and upper heights are conserved, and threaten to inject an extraordinary instability into #3 (below)  - check

3    The rising PNA injects(ed) some sort of intermediate and/or S/stream S/W which interlopes underneath all that in proper timing - a simple way of saying they are in wave harmonic/ or positive interference   - check

It kind of all smacks as a 'chicken vs egg' conundrum but it really is started because there is too much gradient through the total domain region in question - which for the purposes of this discourse is really from 140 W through 60 W.  The flow is faster over the continent, because the continental influence on the total circulation of the hemisphere causes it to draw cold air down, which reinforces said gradient in perpetuity.  The models have difficulty ( observational assumption ) in this area with acceleration being variable from run to run, particularly at the 'flop' end of 'the extended range hose times'.  That's why I am willing to postulate further that range is related in this error.

So... in simpler terms.. .the Pacific is attempting to for once serve us better by sending the +PNA --> +PNAP flex. It's there.   Unfortunately...the models are constantly countermanding ... negative interference by said overabundant gradient problem.  The flow speeds up... the heights are physically limited from N-S orientation... It's like this idiosyncrasy is competing - and what's interesting is that the models are actually creating both sides of that fight. 

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I'm wondering if there was modeling error ( from 10 days ago...) wrt the extended range, and what's happening now west of this arctic boundary

Quite the impressive morning array of obs expansive throughout the entire continental midriff ...with -20 to -7F, 2-m obs everywhere.  I was looking at western Michigan ...everyone is 0F in a WSW wind having come across the entire ~ 50 miles of that Lake Michigan, and -12 on the Wisconsin side ...that's a typical correction from thermal input off the lake that happens in syrupy cold outbreaks.  Then, of course hundreds of miles of brick earth negative temperatures throughout the CP/NP regions.   That KC/Dolphins game ...ha

I get it that it was signaled - more or less... I'm just wondering if this is a rare cold bust for a change, even if by a small margin. 

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There’s a madison river valley HADS site in West Yellowstone that reported -71° yesterday morning (MDSM8). Maybe it’s wrong, but it’s an interesting little bowl there. Maybe it radiates like the moon like Peter Sinks?

image.png

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12 minutes ago, dendrite said:

There’s a madison river valley HADS site in West Yellowstone that reported -71° yesterday morning (MDSM8). Maybe it’s wrong, but it’s an interesting little bowl there. Maybe it radiates like the moon like Peter Sinks?

image.png

I believe that would be an all time record low for the CONUS if valid

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6 minutes ago, radarman said:

I believe that would be an all time record low for the CONUS if valid

Yeah I think Rogers Pass has the record at -70° IIRC? At the least it’s probably worth pulling the sensor and testing it in the chamber. I remember the Allagash ME site breaking the Maine record years ago, but it was found to be too cold. Eventually the Big Black River HADS site broke it with -50°. A lot of these river HADS sites are going to eventually overtake their state record mins since many are sited in pits. There’s quite a few up here that run the coldest in their counties on rad cooling nights.

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1 hour ago, Typhoon Tip said:

How it effects the geometry the atmospheric circulation pattern:  When the effect is large, it exceeds the thermal wind vector component of the geostrophic wind equation, and that forces the curve to open up. 

Hey John,

How is this issue mitigated? Would a larger PNA spike lower southeast heights? I would think a large enough PNA ridge increase would trigger a "tipping point" whereas more energy is conserved and a historic solution bursts into existence....

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Approximately five days out is long enough for the caveats obviously but this isn’t really an eternity away and the synoptic pattern has looked good for a while. I like where we are regardless of what the ops show right now. 

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5 minutes ago, CoastalWx said:

No complaints this far out. A little higher amplitude out west at hr 96 seemed to help. Don’t think there is the capability of a slow crawl, but ceiling is a high impact 12-18hr deal.

I have said this before, but the "slow crawl" crap doesn't really do much for amounts...it just gives Kevin fuel for his "days and days" rhetoric, but the good news is that he'll do it, regardless. The intense dynamics are exhausted within 12-18 hours, anyway in about 98% of systems.

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2 minutes ago, 40/70 Benchmark said:

I have said this before, but the "slow crawl" crap doesn't really do much for amounts...it just gives Kevin fuel for his "day and days" rhetoric, but the good news is that he'll do it, regardless. The intense dynamics are exhausted within 12-18 hours, anyway in about 98% of systems.

Damage is done by then (12-18 hrs) as you implied anyways..whether it’s good or not. 

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5 minutes ago, MaineJayhawk said:

You should not have done that.  There will be "investments"

 

2 minutes ago, 40/70 Benchmark said:

I have said this before, but the "slow crawl" crap doesn't really do much for amounts...it just gives Kevin fuel for his "days and days" rhetoric, but the good news is that he'll do it, regardless. The intense dynamics are exhausted within 12-18 hours, anyway in about 98% of systems.

I was thinking more of the total duration in my statement. And like I said that would be ceiling. 
 

Canadian is not interested.

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Just need to close that off about 6 hours sooner. I could see it was being captured just by the surface depiction that was posted.
gfs-deterministic-ne-z500_anom-5741200.thumb.png.0fd66fbd533bd05f1bcb7b30c420663c.png

#1 on the list… just gonna leave this here. Not saying that’s going to happen obviously, just pointing out the pattern is def good lol9c4bc6fb14a18edcd9ff29440bc28c1e.gif


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22 minutes ago, 40/70 Benchmark said:

Hey John,

How is this issue mitigated? Would a larger PNA spike lower southeast heights? I would think a larger enough ridge would trigger a "tipping point" whereas energy is conserved and a historic solutions bursts into existence....

Oh, I said that backward... let me fix that.

The thermal wind vector increases, the velocity of the geostrophic wind increases, and thus Coriolis parameter can no longer force the flow to curve in time - the centrifugal ( g-force) over comes the curvature imposition of the Coriolis effect.  That's what opens the flow - fuck.  I correct that.  The Coriolis parameter has time in the function... here, I just grabbed this right quick off of Wiki'

f=2\Omega \sin \varphi .\,

The rotation rate of the Earth (Ω = 7.2921 × 10−5 rad/s) can be calculated as 2π / T radians per second, where T is the rotation period of the Earth which is one sidereal day (23 h 56 min 4.1 s).[2] In the midlatitudes, the typical value for ff is about 10−4 rad/s. Inertial oscillations on the surface of the Earth have this frequency. These oscillations are the result of the Coriolis effect.

 

anyway, it's simple - lower the god damn gradient so the Coriolis can curve the flow.

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