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Snowy Hibbo

Long Range Pattern Drivers & Evolution Thread

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I posted that the EPS after I saw the 282 had multiple chances.

I just like the multiple SWs under the block. 0029B69F-0ED8-4C98-A70D-CD6246F8C41A.png.7e3ac9483b0e33e282d773cc9656089f.png.1c9e4766d1d92c16473af1e479b9c1ce.png

 

 

Here's the 5 day mean in the 10 to 15 

20191219_192104.png.1c2c10717507229096dbcd0266879587.png

 

If we filled that gap it would come very close to the 10 day mean before one of the greatest 1 - 2 punch the MA has ever seen

 

compday_vu2ff42WGL(1).gif.0e8847a6576d5e15ceabbb88e7fc67c5.gif

 

I just ripped this from crazy Joe but man thats not too far away. 

 

 

 

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1 minute ago, Analog96 said:

 

I just don't like that air mass Christmas night one bit.

I think we're too warm to do anything but rain, although latest trend is a bit cooler, so we'll see.

 

Theres back side flow, the H drills in from NE.

Thar low cuts to the Delmarva,  you CAD.

 

It's a light snow chance , nothing big.

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2 hours ago, antmasiello_HM said:

 

The RMMs are reacting to higher frequency waves and multiple areas of forcing. This is why they sort of cut through the middle and eventually emerge into W. Pacific. The lower frequency signal will reach the central tropical pacific in the second week of Jan probably. I agree with Eric on that.

 

Use Roundy's statistical guidance for a visual: http://www.atmos.albany.edu/facstaff/roundy/waves/ and more specifically: 2020.png

We don’t enter the colder phases  to after the 10th on those correct? 

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1 hour ago, Snowy Hibbo said:

EPS isn’t a big fan.

B820BB58-1B98-4675-A3C6-22F70A632694.png

 

GEFS likes it better.

4BC69F96-DCC9-4699-AABB-59C7F64DC3C4.png

The positioning of these things are important.


It could work out, but given the progression of the GSDM and the cycle of it, I’d assume it to be a bit earlier. A late torque is better, but it doesn’t really change the narrative. Might improve the short term outcome though, it depends on the strength of the +EAMT of course and how that interacts with the PNA domain 5-10 days downstream.
 

The progression of a gradual change to colder risks in the Eastern US, doesn’t involve a sudden flip to deep cold in Early January IMO.

 

One thing it would help more is to increase the likelihood of that SSW that is making the rounds. Which would help us down the line.

 

The EPS is signaling it. I disagree that it is not.

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17 minutes ago, antmasiello_HM said:

 

I'm not a fan of calling phases warm or cold. I'm also not a fan of isolating a region and treating as if it's the only region, like we've seen in some recent posts this evening. After all, the MJO explains like 25% of the variance. But anyway, the warm pool gets excited during the second week on those charts.

Why aren’t you a fan of that? Wouldn’t p6 be unfavorable for sustainable cold in the east? 

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1 minute ago, antmasiello_HM said:

 

Well, for starters, the time of year matters for the wave train response and what is statistically likely over the US. Being solely in a phase says nothing about the inertial state or changing state since the wave itself, its interaction with other forces, and its influence around the globe all can alter from event to event. Background states affect the way the MJO affects the wave trains and their influence on our weather. 

Very informative. Thank you. So we could be going back to the base state we had in early November? 

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4 hours ago, antmasiello_HM said:

 

This signal has been on the last few runs and fits with the classic tropospheric precursor pattern. It also fits with a classic Niño progression for a mid winter disturbance. The entire evolution with the TPV and this reminds me of 1987.

1986-87 analog showed up a lot in the fall. I did not use it for bad qbo values. But it was definitely there.

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27 minutes ago, Webberweather said:

As the VP200 hovmoller below shows, this is a classic example of multiple higher frequency circulation signals competing for dominance in RMM phase space, hence the dampened/weak MJO. What we're seeing right now is not an MJO in the classical sense but rather a mattering of convectively coupled Kelvin waves (k = 3) projecting onto low frequency modes, which oftentimes occurs in cases like these there's an effective hand-off between lower frequency variability (in this case +IOD >>> +ENSO) and the subseasonal circulation leaves the antecedent dominant forcing signal (I.e. the MJO leaving the Indian Ocean & +IOD). Subseasonal tropical forcing being composed of multiple, fast-moving convectively coupled kelvin waves which are coupled to the extratropical circulation means there really is no single, confined area of the global tropics contributing to the total forcing from the tropics as we try to idealize w/ the MJO. Anthony has said (& noted in the classic Wheeler & Hendon (2004) paper), the RMM MJO only explains 25% of the total variance of U850, U200, & OLR in the 30-80 day band & it's worth noting that the 3rd EOF (via Kessler (2001) & Roundy (2014)) actually explains the advancement towards El Nino conditions which is probably happening at the moment. While some coherent features remain analogous between the composites and the forthcoming pattern, since more variance is being partitioned outside the temporal band (30-80 days) where these filtered U850, U200, & OLR anomalies are frequently associated w/ the MJO, this is going to significantly alter the downstream response over North America the next several weeks & forecasters + weenies/enthusiasts alike should be aware of it.

 

Even though the RMM Index will show the MJO approaching the West Pacific, it's really not that simple in this case.

 

vp200_GFS_anom.KELVIN.5S-5N.png.31aa087d42de9c1b47f2aadf23f0f28b.png

 

 

 

PC 1-3 power spectra from Wheeler & Hendon (2004)

 

RMM Power Spectrum EOFs 1,2, & 3.gif

Which leads to what?

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2 minutes ago, 33andrain said:

That's the setup for our 1/3 storm. I really like that date. And, yes, I realize there are a couple other chances before then. :) 

 

I do agree that once after N/Y we are tracking.

 

The one on the 26th has a slight chance at something light, I like it better for N/E, but I think we have a few days to see where that SW is going to cut S/E.

 

But once into the New Year we may get busy. 

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11 minutes ago, PB GFI said:

This deserves more attention in here.

 

ecmwf-ens_z500a_namer_11.png

I would like to see the ridging get better in Ak for the Early January threat. The +AO and +epo could make it difficult along the coast for snow. We will have threats and it’s early January(not December) but that makes me uneasy 

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