December 20-22, 2018 | Large Scale Storm

[Phased Vort 786]

PREFACE

Operational model support is important, what do you think? 

If you say yes, perhaps you will be thinking now that it´s too much of gamble and waste of time and energy to start a thread for a possible storm 14 to 16 days out, with basically zero, or perhaps zero operational guidance support.

If you think it´s not important, then perhaps you are thinking that this should be an interesting endeavor, worthy of the time and energy used.

Ok. So, let´s continue, shall we? 

There´s a chance, possibility that a storm may form and grace the region with its blessed weather. All rain? All snow? A mix? Impossible to know. And honestly, there´s the no storm outcome as well.

Having that in mind, let us see what we can get from this thread´s time frame only using teleconnections, EPS ensemble data, BSR and a  couple of ESRL/PSD products.

SUMMARY

There exists the possibility during this time frame for a developing area of lower pressures on the East coast (inland or offshore), coming from the eastern GOMEX and SE CONUS area. Another possibility of an area of lower pressures could be in and around the Ohio and Tennessee valleys tracking eastward towards the east coast and ejecting over the Atlantic ocean from somewhere in the Mid-Atlantic region.  

Both areas of lower pressures could impact the thread´s region with some kind of weather. It´s impossible to exact if this possible storm would track inland, tucked to the coast, just offshore, or be a near miss, in the case of a possible SE CONUS genesis. As for the Ohio and Tennessee valleys possible area of lower pressures, the track is also uncertain, obviously. It may track too far north over NJ, father south or even cut through western NY. 

What should be noted is that we may have a storm to deal with, as the Holydays near.

The data used to try to give some sense of support to this possibility, include, as aforementioned, teleconnections (AO, NAO, EPO, and PNA) from various different sources which include ESRL/PSD, GEFS, EPS and EPS 46 days), the BSR and other ERSL/PSD products.

Below, I have illustrated in a simplistic and basic way, the general track areas for the lower pressures that could develop, as described in this summary. Please, take a look:

On the next page, we will cover the previously supportive or not so much, mentioned data with images.

 

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Let´s start with the BSR.

Looking at both the 500mb and surface depictions, there´s seems to be little support for a storm during this time frame, aside from a more noteworthy signal one day earlier on the 18th of December.

Perhaps this could be a case in which a storm is delayed or could track in and around the coastal plain. However, acknowledging the BSR data shown for this time frame alone, a storm should cut through western NY.

500mb                                                                                         Surface

So, support for a storm exists, but not the kind of storm most would want.

 

Now on to a couple of ESRL/PSD products:

These do show some support, as there seems that a trough will be digging and moving towards the east coast. The magnitude of the trough (how amplified and strong), of course, cannot be set now.

Ensemble Mean 500mb Height                                              Sea Level Pressure / 1000-500mb Thickness

 

Hence, there is support for a storm as well, albeit, it may not be a powerfully amplified trough and flow.

 

Now we get to the teleconnections from various different sources.

They include the AO, EPO, NAO, and PNA. Some of them are not favorable, others are while some are in that highly regarded transition period.

First off, we will check the AO.

EPS 46 Days                                                               EPS                                                                       GEFS

All sources indicate a negative AO. Both the EPS 46 days and the EPS, show the AO closer to neutrality but does not quite make a transition.

Negative AO bodes well for colder temperatures over the eastern CONUS. Being that the values are not that negative, it´s possible that the cold air, won´t be as deep or strong.

 

Now, a look at the EPO.

EPS 46 Days                                                               EPS                                                                       GEFS

All source indicate a positive EPO. They show small positive values and approaching neutrality. However, the do not quite start making the transition.

Negative EPO helps keep the eastern CONUS colder. So, this kind of EPO along with the AO, may be saying that there should be cold air in place, but not strong in nature.

 

Now, we check the NAO.

EPS 46 Days                                                               EPS                                                                       GEFS

All sources indicate a negative NAO transitioning to neutrality and perhaps actually going into positive territory as can be seen on the EPS 46 days data. 

Negative NAOs support blocking of some sort. A transitioning NAO period is usually good for east coast storms.

 

Now, we get to the PNA.

EPS 46 Days                                                               EPS                                                                       GEFS

All sources indicate a positive PNA.

A positive PNA means ridging over the western US, which in turn helps troughs get established over the eastern CONUS.

Now to finalize the teleconnections, below please see the ESRL/PSD.

Not quite in range, but we can see that PNA is quite positive, beneficial.

The NAO going neutral, perhaps transitioning to negative. If so, it´s beneficial.

And the EPO rather positive, not beneficial. In case it gets to neutral or transitions to negative by the time in discussion, that then would be a plus.

 

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In short, all in all, we have some good indications that a storm could be in the region during this time frame.  And considering all the data discussed, in case a storm that brings snow to the eastern seaboard comes, we should not be surprised. At the very least,  we will learn more once again.

Whenever you feel the time has come, please join the discussion and possible tracking. 

Remember, there´s no model support as of now.

Have fun!

 

 

NOTE: The thread date and title will most likely need to be adjusted as we get near the time frame.

[Phased Vort 786]

First appearance of some kind of storm on the GFS for this time frame.

Just posting to record and for posterity for the future.

December 07, 2018 00Z GFS:

[Phased Vort 786]

December 07, 2018 06Z GFS:

[PA road DAWG 506]

I think Pocono snow create a thread for this.  He just had the dates off by a day or two

[Phased Vort 786]

December 07, 2018 00Z FV3 GFS has a phased storm near Chicago.

[UTSwiinii 1,862]

12 minutes ago, PA road DAWG said:

I think Pocono snow create a thread for this.  He just had the dates off by a day or two

I  don't think that is the case, but if they meld into one another, appropriate action will likely result in a merge. 

[jdrenken 1,303]

36 minutes ago, PA road DAWG said:

I think Pocono snow create a thread for this.  He just had the dates off by a day or two

At the end of PV's BSR gif you can see Pococono's storm coming in view over the South.

[Phased Vort 786]

Latest EPS teleconnections show: 

- AO - 

+ EPO moving towards negative

- NAO - (basically neutral)

- PNA (not good)

 

[Phased Vort 786]

GEFS teleconnections:

- AO 

+ EPO (basically neutral)

- NAO (basically neutral)

+ PNA 

 

 

[PA road DAWG 506]

Gfs seems to still have the threat but just well offshore at the moment, and less organized. 

[UTSwiinii 1,862]

All I'll say for now is that we might apply a "JD Rule" for this time pd. 

Something like, when there is a warm up in winter, watch out for what follows. 

[snowlover2 172]

Yes please.

[morgdotz 63]

I’m dreaming of a whiiiiitttteeee Christmas 

[Uscg ast 780]

13 hours ago, Phased Vort said:

GEFS teleconnections:

- AO 

+ EPO (basically neutral)

- NAO (basically neutral)

+ PNA 

 

 

The PNA looks essentially neutral here, which I would think plays more towards an inland track especially with AO in only slightly negative territory and the EPA neutral. 

[Kohler7 24]

Is that freeze line in Orlando FL?
I go to Jacksonville for christmas (family)......  So much for escaping the cold.

[Phased Vort 786]

December 08, 2018 00Z FV3 GFS:

 

Tries to develop as a big trough drops over the  western southeast CONUS, after a low pressure tracks into the Mid West on the 19th.

[Phased Vort 786]

Dec 08, 2018 00Z GFS:

 

This version has a clipper redevelopment, perhaps a Miller B and then deep from the trough, albeit far offshore, comes a developing low pressure from the south.

Off course, these details will be sorted out as the days pass.

[Phased Vort 786]

Dec 8, 2018 06Z GFS:

[Phased Vort 786]

Dec 8, 2018 06Z FV3 GFS:

Very similar to the 00Z run. A slow pressure tracks over the western Lakes and then deep from the trough base, a new low pressure develops and tracks to the Mid-Atlantic.

[brodoser1 133]

Iam dreaming of a white Christmas 🙏🏻

[Phased Vort 786]

Dec 8, 2018 12Z GFS :

 

[Phased Vort 786]

Dec 08. 2018 18Z GFS:

 

This run has only the northern agent. No southern stream partner.

 

[Phased Vort 786]

Dec 8, 2018 18Z FV3:

This is a very interesting run. It has some players that could be best friends if they get to understand each other.

[mbaer1970 25]

[Phased Vort 786]

12Z GFS: