Tonight's ECMWF on the weekend system

[Erica]

Tonight's ECMWF is pretty consistent with the things I talked about last night. Exactly how this system behaves depends mostly on whether the mid week system bombs out and becomes the new 50/50 low.

Tonight's Run of the ECMWF does have that taking place.





And it also has the block near England, retrograding back across the Atlantic. the 50/50 low however seems to be slightly displaced southeast of Newfoundland, which is the position you would want it to be for optimal effect on the synoptic pattern.

The 50/50 low should sharpen the wavelengths and possibly help to turn the NAO slightly negative. But most of that will depend on where the retrograding block ends up.

The Polar vortex is in a climatological position over baffin Island, and relatively weak, so there would not be that strong of a jet in the confluence underneath it to prevent shortwaves from digging. There is also some evidence of a PNA ridge across the western part of North America. With the 50/50 low in place, that is one of the three features which we need to see for the s/w coming into the rockies to be forced further south, to get around it.

Also on day 6, we have a closed low just west of spain which could be siggnificant too.



The ECMWF tonight, has been taking a step in the right direction, with keeping the surface low further south than what the operational GFS runs have recently, and does re-develop it off the coast on Day 7.



The 12z GFS had the same thing, but the 50/50 low was not as developed.



Anyway, my theory is simple, the mid week system bombs out and becomes the new 50/50 low, which causes the s/w coming out of the plains to take a more southeast track. The initial system moves to the Eastern Great Lakes region, and then re-develops along the east coast. We should have a better idea on whether or not this is going to happen once we see what transpires with the mid week storm.

This afternoon's 12z UKMET had the weekend system taking a much more suppressed track than the operational GFS,

[Stormsfury]

00z GGEM at 144 hours offers some support as well..

GGEM 144 hours.

[Erica]

Yea, and the block is nosing back toward greenland too, but the 50/50 low isn't looking too great.



The GFS is also trending in this direction.



Though, the 50/50 low is a bit more impressive. The s/w is also taking a track much further south.

[Erica]

Right now, the European seems to be the outlier.

[Stormsfury]

It's a toss-up with all the camps ... I haven't seen the 00z UKMET yet (I don't think it's out yet ... so it's wait and see time) ...

[Erica]

The GGEM was ahead of the rest of the models last night, and seems to be again tonight. I don't trust the GFS output since it's been run off of bad UPA coverage, and the ECMWF seems too far to the northwest, though it too, has also trended further southeast.

[Erica]

What might be more important, now that I actually think about it is what's going on in Europe. See the closed low west of Spain underneath the block associated with the split in the flow.

[Stormsfury]

Very interesting ...

[Erica]

It would teleconnect well with a closed low in the eastern part of the country, just like what happened with the early December Nor'easter.

[Erica]

That is very interesting, we have the split flow, and closed low over the lower Mississippi valley, not to mention the 50/50 low and blocking headed back toward greenland. Too far out though to really speculate on, but it would be nice. lol, even for you since the low is already pretty deep, it could have some wrap around moisture.

[Erica]

the 168 hour GGEM for the weekend event does bomb the low out to 987mb, but it tracks too far out to sea.



We'll have to see what the Ensembles have to say.

[Erica]

What's probably best is a meadium between the ECMWF and GGEM solutions which since the ECMWF is pretty far inland and the GGEM out to sea, the track would be up the coast, so it probably is something to watch.

But thats alot of guesswork, and besides, we need to see what the mid week event does before we can really focus on the weekend event.

[Stormsfury]

That is very interesting, we have the split flow, and closed low over the lower Mississippi valley, not to mention the 50/50 low and blocking headed back toward greenland. Too far out though to really speculate on, but it would be nice. lol, even for you since the low is already pretty deep, it could have some wrap around moisture.

And extrapolation. OF course, we know that the GGEM's serious warm-bias, PLUS taken at face value should easily tap into the cold air with the progged 1044 mb HIGH in Eastern Canada ... and with the 50/50 low, should already have some available cold air in place, with the ability to tap into a fresh source on the back side of the low ... although, the 500mb/SFC low seem to be too far spaced ... but hey, it's 10 days out .. ... Otherwise, I agree that the overall pattern teleconnects well ...

[Erica]

It would probably be a bit further back to the Northwest. But yea, it is 10 days out, plenty of time for changes.

[Guest]

Well i would be happy with a track across central/southern KY and NOT into OH or ofcourse north or west of the state which im not holding my breath on. Nice to see a different set up then we have had for the last week or two though. One other good thing is that this could be comming on a weekend which you all already know about that theory. Thought i would mention that. You two pretty much covered the rest!

Either way great discussion SF and Erica! Midweek will probably tell the story which means yes we do have some time to watch whatever becomes of this possible event.

[Erica]

Thanks, it's interesting that you bring up the SECS/weekend rule. It also seems like most of the Major Carolinas and Southern Mid Atlantic snowstorms happen during the Middle of the week.

New England and Interior Northeast and Mid Atlantic events seem to be be just as common on any day of the week.