ORH_wxman

The agreement is now pretty damned good. EPS looks a little better overall because the AK ridge on the EPS is stronger....but the anomalies are mostly matching in the right spots to eachother now.

There are quite a few EPS members that give a good shot of snow for the 12/16 system. There's even a small handful that are mostly/all snow.

Yeah the big western PNA ridge isn’t happening I don’t think for now (maybe in January if Ray has the right idea?)….but I love that split flow -EPO/-PNA/weak -NAO look. The EPO ridge is pretty Far East too.

The ULL is so wrapped up to the west it’s trying to yank it NW. it’s fighting the block the whole time though. It eventually succeeds in a limited fashion. It unlikely to play out that way though. If the block is going to sit there in the Davis Strait with a 50/50 trending southwest, I think 12/15-16 will keep trending south too. We can get cutters with a big block there but you typically need a lot of nuances to line up. It’s kind of the opposite of when you have no blocking and a semi-hostile PAC…we’re trying to thread the needle for snow events…in this case, you have to thread the needle for a full cutter. It can happen, but they usually play out messier than that with secondary redevelopments, etc.

Getting closer.

We'll see how the airmass is prior tot he storm....this run had a very chilly airmass advected down int he wake of 12/12 when that PV lobe retrgraded into Maine....it leaves us with a pretty cold airmass. This is 12/14 at 12z. IF you start crushing the system off to the west a little sooner, then you are going to hold this airmass in a bit better upon approach.

NNE may stay frozen on this Euro run for 12/15-16.

It happened in 1997....I think 12/11/97 (ironic its almost the same exact date is this upcoming system)....part of S CT got 5-8" while pike got skunked. South of pike into N CT got like 2-5". ORH prior to that had a 5" event in November, but hadn't gotten warning snows yet. They did get 18 inches though 12 days later on 12/23/97. I remember the 12/11 system though because it was originally forecasted to be 3-6" for ORH and then in the final day they kept cutting amounts and settled on 1-3" and we actually got zero. About 10 miles south had 2-3". I remember seeing cars driving north into the city on 290 with snow all over them and it made me furious.

Euro trying to push the 50/50 PV lobe into N Maine after the 12/12 system. -20C 850 temps....maybe CAR will be cold afterall.

That's close to something a lot better...if we can just curl that little vortmax up into SE SNE.

More confluence but that shortwave is significantly deeper, so it's fighting it. Should be a good hit at least for western zones....we'll see if it can get enough moisture east.

Euro is looking a bit more robust with shortwave for 12/11-12/12....but the confluence to the northeast looks much stronger. The block is flexing its muscles this run.

Mike Ekster is the creator of the term. We kept discussing on eastern in Dec 2007 on how to decribe all these events that kept walloping us aloft with southwest flow but stayed cold in the low levels and he said "they are basically just southwest flow events" and then we started using the term on there and it stuck.

Might never warm sector though in interior on that run. GGEM had a decent shot of ice over interior on that system. Still need a little more to get that one snowier.

Still 4.5-5 days out....everyone should remember that. Lots of room to move either direction. The hedge is south because of the steroid Davis Strait block pushing the 50/50 ULL S or SW. But it could easily come in more amped too on future runs if there is a bit more phasing of energy out to our west.

GFS is stronger with 12/11-12/12 shortwave but its fighting stronger confluence too. It's a good hit for CT, but eastern peeps struggle to saturate.

Yes that can happen for sure. There's different flavors of SWFEs. The ones where the secondary tracks over SE MA/RI can warm up those southeast coastal regions pretty good. There's also ones like 12/13/07 which stay mostly snow even in SE areas.

Many times, SWFEs were at some point cutters on the models and then they trended colder. That is one reason you don't want to freak out every time you see a cutter out in la-la land on the models....esp if there is some cold hanging around to our north.

SouthWest Flow Event. That is describing the flow aloft, not at the surface. Typically those systems where it might snow on the front end as a storm trying to cut to the west hits a strong high to the north....we'll frequently flip to sleet and ZR and maybe even rain in those too, but you never really torch in the warm sector because the storm tries to redevelop and track over the Cape. So you might get this type of progression for weather: 1. Snow on the front end...temp in the 20s (maybe 2-5" of accumulation) 2. flipping to sleet, temps still in the 20s but creeping up to near 30F 3. flips to freezing rain for a few hours as temps continue to clibm near freezing 4. Temp finally inches above 32F and you get cold 33-37F rain for a bit before dryslotting.....then temps eventually cool back below freezing behind the storm. Some SWFEs are colder than others...and sometime we can stay mostly or all snow. But the above is probably the most classic representation of how the weather plays out in SNE during them.

There's always been a few ensemble members toying with the idea too....again, low probability initially (but now increasing quite a bit), but when you consistently have like 10% of the members showing something at 6+ days out, then you should at least consider it as a real possibility even if you wouldn't actually forecast it on your 7 day outlook.

Late next week is the 12/15-16 system....if that tracks to our west, then it will wipe out any pack from 12/12.....but there's a chance we end up with more of a SWFE and in that case, any pack would probably survive at least in the interior. But lets see what happens for 12/11-12/12 first. That system is going to affect the one behind it. We need a pack to protect first.

It looks colder behind the 12/15-16 system....doesn't look downright frigid at the moment, but a generally seasonably cold pattern. When the EPO ridge spikes like that though, there's always a chance we get an arctic shot, even if it's temporary. But right now, my money would be on a bit below normal temps when you have a split flow -PNA/-EPO/weak -NAO.

That big ocean storm you see way out to the east is the 12/11-12/12 system. So clearly that system will have an impact on what happens 12/15.

You can see it on the individual ensemble map....there's a cluster of redevelopers