John1122
Member
Polar Vortex headed for the Great Lakes?
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Pattern January 2020 - Operation Thaw Alaska
- Thread starter KyloG
- Start date
Polar Vortex headed for the Great Lakes?
Look at that -AO, never thought I would see it again this January on 1 model run
Winter Uncancel, number 2 or 3....
John1122
Member
Looks like the GFS is going to have a cold shot, a brief warm up ahead of the next front, then unleash the hounds with another shot. Tons of cold air and it's in our source region for once.
Gfs has slowly been getting colder because it has been trending towards a more poleward ridge near AK and has been trending towards a +PNA 
You mean 9 or 10.
Just before everyone jumps on the cold train remember at this point it is still a likely progressive pattern until we actually see some sort of powerful -EPO set up. Just remember this if the models ensemble mean start showing ten days of cold which gets whittled down followed by ten days of torch.
No comment 
No something a little more like this ?
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Look at that ridge building closer to being over Alaska you have to love the trends tonight
Not quite yet..still looks ugly to me but general consensus is a brief shot of transient cold air towards the end of the first week in January..EURO with a storm signal tonight towards the end of the run
John1122
Member
Euro and Canadian had the same storm tonight. Similar track but the Euro is a little further south. Massive winter storm for N Arkansas, N West and N Central Tn to Kentucky that run. Almost a banana hp look but the western center is north and the eastern center is weak so it cuts the Apps. Could end up being a significant storm threat or could be another cutter. Hope it turns into something worth tracking.
I’m just not sure the obsession with the -EPO. Not directed at you, Nick. I mean maybe when it’s coupled with a +PNA or a -AO? I just don’t see how it’s that beneficial of a teleconnection by itself. Seems like a recipe for a troughy west coast. Maybe someone can elaborate on this in the morning. I genuinely want to know. The GEFS has a similar look near AK towards the end of the run and you see how much it benefits us..
-EPO can give us some of our coldest weather, with literal cross polar flow, only issue is that at time it can hurt a pattern and even encourage a SE ridge
John1122
Member
That's not quite a beneficial -EPO. Move the center of those heights about 750 miles east into the Gulf of Alaska. It bulges north across Alaska at times and turns the flow across the pole and brings Siberian air straight into Eastern North America.
When the EPO does that it can overwhelm the Atlantic. Winter 2014-15 saw the -EPO put the Eastern U.S in the ice box even with a +AO/+NAO.
When its positive a LP spins in the gulf of Alaska and sends Pacific air screaming across the country and we're all warm.
Yeah the euro and it’s ensembles are showing the ridge much further east which would have drastic impacts to what the US looks like
Webberweather53
Meteorologist
All -EPOs aren't created equal, you get a west coast trough/-PNA when the -EPO is suppressed equatorward & displaced westward. Need the ridge to be centered closer to the Yukon Territories and literally over Alaska to benefit from it.
Webberweather53
Meteorologist
Pretty rare to see literally the entire CONUS have below normal 850s
Signs of 2014 Winter.
Good EPO, ridging into AK with a positive PNA 
Bad EPO, ridge displaced to the west, so colder air is dumped into the western US/Midwest
time to cancel winter EPO, hard pattern to break, ugly GOA ridge, last February in a nutshell, deeply negative PNA, Seattle gets everything while we torch 
Bad EPO, ridge displaced to the west, so colder air is dumped into the western US/Midwest
time to cancel winter EPO, hard pattern to break, ugly GOA ridge, last February in a nutshell, deeply negative PNA, Seattle gets everything while we torch
Webberweather53
Meteorologist
To reiterate from yesterday, we really need to keep a close eye on the North Pacific storm track the next week or so.
Small changes in the placement, amplitude, & orientation of the Okhtosk trough & downstream ridge in the NE Pacific & Alaska will make all the difference here. For the SE US, there's a very fine line between a warm & an extremely cold pattern with little room for in between.
Small changes in the placement, amplitude, & orientation of the Okhtosk trough & downstream ridge in the NE Pacific & Alaska will make all the difference here. For the SE US, there's a very fine line between a warm & an extremely cold pattern with little room for in between.
Basically the fine line between a wintry pattern and a pattern supportive of severe weather with a flexing SE ridge and shortwaves ejecting out the west
Webberweather53
Meteorologist
Yep, in terms of sensible impacts anything is on the table atm & one of the two extremes is more likely than the middle of the road solution/ average temps. Even in some of our best wintry -EPO patterns, Florida is often still baking.
Wouldn’t mind both, gotta love this upcoming pattern if you love severe and winter weather, either one is a win
tennessee storm
Member
I second that in a heartbeat... this boring meh weather is killing me lol
Probably won’t last but I’m seeing some big dog snow storms and small storms on the 6z GEFS under 10 days. Looking like some of the EPS members
Website to find GEFS members
https://weather.cod.edu/forecast/
Website to find GEFS members
https://weather.cod.edu/forecast/
No, it's more of if you love rain or winter weather. Not gonna see many interesting severe events with the roaring subtropical jet.
Dang, Euro close to dropping the hammer.
John1122
Member
06z dropped a nice event imby on the Upper Cumberland Plateau in East Tennessee, as well as NETN, SEKY and SWVA and the far western NC mountains. Looks a little faster than the Euro/GGem and a little further south but is in the same ballpark time frame as they showed earlier. Decent winter threat that hopefully can be reeled in over the coming days. Had pretty good luck doing that with the few winter threats we've had West of the Apps so far this season. With how badly the last 3 years has gone, and with what I have down, even one event like that the rest of winter would feel like a huge bounce back year. Very cold few days in there too.
Well Larry has chimed in last night with a forget about it in the southeast for a while, maybe a long while.
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Looking over the EPS ensembles in the long range, still not much agreement in where the western ridge sets up. That said seeing many more members dropping the PV close to the Hudson.
Webberweather53
Meteorologist
No this isn't true at all, a strong subtropical jet doesn't = lackluster severe, there's more to it than that. Actually, the presence of the southern jet is an additional source of barotropic kinetic energy & baroclinic energy that can be converted into eddies, leading to stronger surface cyclones & SRH, etc, the key is its latitudinal position.
A NINA-esque SE US ridge pattern coupled w/ a strong southern jet being deflected northward around the SER is a good pattern for severe.
Webberweather53
Meteorologist
Rather unsurprisingly, the GEFS is trending towards the more favorable EPS solution. A slower, equatorward, & more neutrally tilted trough axis is evident in later runs near eastern Russia >> favors stronger, more poleward -EPO in the 2nd week of January.
While that is true, the subtropical jet can also flood mid-level moist air which really hurts the EML. Sure you can get severe weather, but the really active outbreaks that people who like tracking severe weather want to see are hampered by messy storm mode and weak lapse rates.
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Webberweather53
Meteorologist
The subtropical jet doesn't flood the continent w/ moist air in the mid-levels, the subtropical jet is actually higher in the upper troposphere than the mid-latitude jet and is roughly in geostrophic balance so it's not advecting anything to begin with.
Im talking about more moist southern stream systems, not the jet itself.
Webberweather53
Meteorologist
"the subtropical jet can also flood mid-level moist air which really hurts the EML"
There's a huge distinction between the eddies within the jet and the jet itself, which you were clearly talking about in the previous comment although you've subsequently denied it. EMLs rarely reach the southeastern US because they've usually been mixed out even in the most favorable patterns. You also don't want the mid-levels to be so dry that when parcels ascend, they entrain dry air and the updrafts collapse. Coupled w/ strong shear at this time of the year updrafts would be further enticed to collapse in the presence of an EML, plus the lack of an EML is rarely the limiting factor for severe in January-March. Having an EML or the lack thereof is hardly a back breaker for severe weather in general in the SE US. It's sometimes present in the largest outbreaks but again it's not a necessary prerequisite outside the southern plains for getting an outbreak. In any case, the discussion of severe weather outbreak and whether or not this pattern would support one is superfluous here because there's far more needed than a nice synoptic-planetary scale wave pattern and its over a week away.
However, getting back to @Myfrotho704_ 's initial statement, the longwave pattern being shown in the longer term is in fact favorable for some severe weather in the SE US even w/ a strong subtropical jet which is deflected northward around said SER and again this STJ is not actually what's advecting mid-level EMLs into the southern plains.
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Good grief, really?
Webberweather53
Meteorologist
Well, the bolded statement is true because you were at first discussing the STJ and then later you moved the goalposts and said you were talking about the eddies in said jet. There is in fact a pretty big difference between the two, the subtropical jet is a waveguide and is found exclusively in the upper troposphere, the other is obviously the waves themselves which have large depth in the troposphere and may extend throughout most of the column. The eddies may advect EML but again it's really not a necessary ingredient given the time of the year and location. A strong EML + strong shear + weak CAPE often = collapsing updrafts & very disorganized convection, if any. In this sense, the EML may hurt, not enhance deep convection
I was mentioning it in a general sense. Im not gonna write a novel when 99% of the people here could have read and understood what I said. Im not denying anything. If you really want to think Im moving the goal post, go ahead.
Im not exactly sure we are on that much a different page as far as severe weather goes. Sure, this is a pattern for some severe weather, I don't deny that. That said, having posted with Tennessee Storm for years and seeing Myfro's previous posts and being a severe weather junkie myself, seeing messy storm modes hindered by weak lapse rates is not a "severe weather" pattern for us.
Edit: Now that I think about it, I'm not writing a novel in any case.
ForsythSnow
Moderator
GEFS looks ok this morning, but the EPS has less support. Still a few members there with snow, but at least there's something. And this is around day 9
