Re: Long Range Thread 13.0

[Frank_Wx]

The PAC ridging keeps trending stronger on the EPS. It's literally arousing.

[billg315]

The PAC ridging keeps trending stronger on the EPS. It's literally arousing.

Yeah you can see it rising out there clearly. That's the ridge I'm referring to. lol

[nutleyblizzard]

The PAC ridging keeps trending stronger on the EPS. It's literally arousing.

Taken verbatim, if we don't see a MECS if not a HECS with the upcoming pattern change I'd be stunned. That's textbook right there.

[CPcantmeasuresnow]

The PAC ridging keeps trending stronger on the EPS. It's literally arousing.

Taken verbatim, if we don't see a MECS if not a HECS with the upcoming pattern change I'd be stunned. That's textbook right there.

An area wide Mothrazilla at a minimum.

[Math23x7]

An area wide Mothrazilla at a minimum.

And The Conservancy will still record a trace of snow out of this.  Facts.

[rb924119]

You guys crack me up ahahaha btw Frank, a video explaining my thinking will be out later this evening.

[Dunnzoo]

Let's find a bar near the park and measure it ourselves when it comes. I think we have a few trained spotters on here (myself included) that could send in the reports.....screw the conservancy

[dad4twoboys]

Let's find a bar near the park and measure it ourselves when it comes. I think we have a few trained spotters on here (myself included) that could send in the reports.....screw the conservancy  

Why not call the conservancy and ask them what bar their staff goes to to hang out during the snowstorms.

[Frank_Wx]

Dad...that's hilarious. So true.

[sroc4]

After examining the data this morning, the following looks reasonable to me:

 

1) The initial wave-1 assault on the stratospheric vortex Jan 22-24 will be insufficient in inducing an official warming event. Meridional heat flux and momentum flux becomes more zonal by D10, reflective of a slight decrease in tropospheric wave driving. However, as I have mentioned, the tropospheric precursor pattern will begin to strengthen the Aleutian stratospheric high once again, setting the stage for another increase in wave-1 amplitudes, probably to at least 1400 gpm at 10hpa by the very end of January. This will act to increase geopotential heights across Canada, North America, and the polar regions, with the vortex displaced off-pole. The question becomes, will the wave forcing be sufficiently potent to close the deal? Namely, a continued push of the vortex into Europe w/ a classic displacement event. This will aid in determining the longevity of the upcoming pattern.

 

2) MJO robust / coherent propagation through P1-2 (see WWB) will result in the lagged tropospheric result with the development of mean troughing in Nino-esque locations. The Aleutian trough and concomitant W Canadian / AK ridging will act contemporaneously with the displacement activity through the stratosphere to raise geopotential heights in the EPO/PNA domains.

 

3) The AO and NAO will remain largely positive through the beginning of February, reflective of the aforementioned circumstances.

 

4) The period of favorability should peak in the first 10-11 days of February as the MJO forcing impacts the troposphere, coupled with the stratospheric progression. In the first 10 days of February, a snowstorm is highly probable somewhere in the Eastern US.

 

5) Beyond February 10th-11th, there are two possible pathways. The low frequency / interseasonal Nina walker cell should return coincident with the decay of the MJO, possibly leading to a worsening of the Pacific pattern as we approach mid February. The question would then become - do we hand off favorability to the Atlantic? This will only be the case if wave driving is sufficiently strong to induce the full SSW in early February. Otherwise, the off-pole displacement will be subsequently be followed by reconsolidation of the vortex at the pol and lowering geopotential heights by week 3. The outcome of the stratosphere is indeterminate, but there will be enough displacement activity to produce a conducive regime for early Feb.

 

Conclusion: the largest window of opportunity of the winter thus far begins near the end of Jan, through the second week of Feb. The pattern may turn more unfavorable thereafter, but I cannot guarantee that right now.

Tom this is your most encouraging update thus far. Ill take it!!

[sroc4]

Thank you, Scott haha

You bet Ray. You were the first one that I heard discuss this pattern in your video on the 9th. It may not end up a snow event for us, but its looking more and more likely New England gets a snow storm.

[Armando Salvadore]

Hm, there are discrepancies amongst the GEFS and EPS for the end of the month (18z GEFS/ 12z EPS). However, given the GEFS MJO forecast amplitude and the SOI switch which enhances the pattern adjustment, i think i'd lean more on the EPS suite here. I also believe the GEFS is just slow on adjusting to the intraseasonal forcing that is going to occur. Then again, it literally shows a WQBO/-ENSO composite with Aleutian ridging and a mean trough axis over the west. Anyway, as i've said, i believe the EPS has a better handle on this.

[Frank_Wx]

Hm, there are discrepancies amongst the GEFS and EPS for the end of the month (18z GEFS/ 12z EPS). However, given the GEFS MJO forecast amplitude and the SOI switch which enhances the pattern adjustment, i think i'd lean more on the EPS suite here. I also believe the GEFS is just slow on adjusting to the intraseasonal forcing that is going to occur. Then again, it literally shows a WQBO/-ENSO composite with Aleutian ridging and a mean trough axis over the west. Anyway, as i've said, i believe the EPS has a better handle on this.

Someone on twitter said the GEFS and EPS are at odds. I disagree. Both show blocking returning to the Pacific except the GEFS don't have the PNA. As long as the MJO wave propagates as expected, the PNA should spike.

[Armando Salvadore]

Here is the 18z GEFS mean.



Here is the 12z EPS



Big difference is what they do with that Aleutian vortex. GEFS seems to have a very weak signal and is allocated west of Hawaii while the EPS is much more amplified, and south of alaska. The tropical forcing propagation argues for a look like what the EPS has, which is why i said i side more with the ECMWF suite. I believe the GEFS does correct more east with the trough axis, but hey that look is still a cold and stormy depiction. Both still show pacific blocking as you mentioned Frank. That is a no brainer given what will be happening over the west pacific.

[sroc4]

Here is the 18z GEFS mean.



Here is the 12z EPS



Big difference is what they do with that Aleutian vortex. GEFS seems to have a very weak signal and is allocated west of Hawaii while the EPS is much more amplified, and south of alaska. The tropical forcing propagation argues for a look like what the EPS has, which is why i said i side more with the ECMWF suite. I believe the GEFS does correct more east with the trough axis, but hey that look is still a cold and stormy depiction. Both still show pacific blocking as you mentioned Frank. That is a no brainer given what will be happening over the west pacific.

They look at odds to me.  Honestly if the Aleutian trough is correct on the EPS you get the +PNA/-EPO couplet go up; however, if the GEFS is correct the most anomalous thing on that map is the persistent -PNA trough.  The -EPO is showing here which will lead to similar pattern evolution to what we've seen thus far; ie: big cold pool building in western Canada a piece of which breaks off and digs into the central plains and heads east from there, but the -PNA keeps the mean trough in the SW CONUS.  

Honestly looking at the MSLP Anomaly maps for the equatorial Pac for the next 10days the -SOI does not look to back down that much against the base state which should lead to enhanced convection on or near the date line. The -SOI (HP in the Darwin area relative to lower pressure in Tahiti) should provide the conditions in the trop Pac for the MJO to enhance the Aleutian trough as depicted by the EPS package.  

I am going to try not to over analyze the LR models because they will, as they typically do, take time to see the big picture when changes are amiss.  When you have such stark differences as seen above you have to ask yourself which is handling it better.  If the MJO strength and phases are correct then the GEFS package is at odds with its own MJO forecast by leaving the mean trough in the SW.  Since both EPS an GEFS MJO forecasts are very similar in evolution, coming out in phases 8-1-2, I have to believe the EPS is handling the look of the LR much better.  Again this far out we cant go crazy with models run to run, but rather follow the progression of the SOI index, the MJO, and the wave 1 attack on the horizon to the stratosphere.

[Armando Salvadore]

Bingo Scott. GEFS and EPS both show very similar tropical forcing propagation. You'd assume we'd see what the EPS is painting. Again, its not about guidance shows, but its the ability to study the aforementioned indices, then watch guidance gravitate.

[rb924119]

Frank, for some reason I'm having trouble explaining myself, probably because I'm tired lol I tried a few takes and they just aren't coming out well. First thing tomorrow I will have my video for you all. Sorry for the delay, ladies and gents!!

[Isotherm]

Agree Scott and Armando. GEFS is likely wrong and not handling the forcing progression correctly.

[skinsfan1177]

This supposedly torch looks to keep getting muted as time goes on. Also the 27/28 looks like we maybe tracking this one

[skinsfan1177]

[nutleyblizzard]

Big changes from last nights long range 00z GEFS. Much better ridging out west and toughiness east. More in line with EPS.  Major pattern reversal is coming folks!

[algae888]

Big changes from last nights long range 00z GEFS. Much better ridging out west and toughiness east. More in line with EPS.  Major pattern reversal is coming folks!

yes nut and also this weekend we need to watch as now all models have systems going under us. they are not handling the anomalous ridging in e/ Canada very well. no +10 departures on euro for cpk this entire week. nws forecast has on day at 50* rest in the mid 40's. fun times ahead
edit: nws disco conveys my thinking...
Models are in good agreement on ridging building Wednesday night
through Thursday across the eastern states as the trough moves
offshore. As ridging continues to build into Friday, another upper
trough will dig towards the north Atlantic from SE Canada. With this
pattern aloft, high pressure will build over the region Thursday
into Friday. Above normal temperatures continue in the middle and
upper 40s. Some readings near 50 are possible in the NYC metro. The
warmest air in this pattern appears to stay well to the south of the
Tri-State as we will be under the influence of NW flow aloft and
light N to NE flow at the surface.

Energy from slow moving upper trough across the SW US and Plains is
progged to eject out towards the Ohio Valley on Friday and then get
caught underneath strengthening ridging aloft. This energy may
approach Friday night and bring enough moisture for precipitation.
However there is a large amount of spread on the amount of lift
available as well as the strength of the energy as it gets to the
coast. Despite this potential energy bringing a brief chance of
precipitation Friday night, anomalous ridging continues to build
aloft. The ridge axis may move offshore Sunday as a more significant
upper trough and low pressure approach from the west. Temperatures 5-
10 degrees above normal continue this weekend.

[Frank_Wx]

As Nutley mentioned, and what we all predicted, the GEFS reverted back to showing major Pacific blocking and trough placement on the EC to match the EPS.

The pattern after the 27th will rock. Snowstorm signal growing stronger.

[Frank_Wx]

The GFS has been very consistent, as well as the EPS/GEFS, on showing a major Strat PV weakening in the long range. We could be looking at a prolonged -EPO period if this comes to fruition.

[Frank_Wx]

AO/EPO forecasts from the ECM

[Frank_Wx]

An even stronger 850 hPa amplitude WWB east of the Dateline is forecasted on latest GFS Hovmoller.



Interesting ENSO battle taking place at 200hPa



Convection apparent...

[rb924119]

Video upload in progress. Please be aware that I could be completely off on this, and quite honestly it is looking that way with today's 12z's so far, but I am not ready to write this off just yet; not until that energy at least gets some sampling and we see how the southern stream energy evolves.

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