December 2018 Pattern And Forecast Discussion

[John1122]

The Canadian has a very low starting miller B hybrid that cuts NE into a banana high set up before jumping from Western KY to a redevelopment in the Carolinas.  Bizarre and unlikely solution. 

[jaxjagman]

MJO looks like it might be fixing to get into the IO  then go back into the COD and come back out into IO once again maybe into Jan,it's not a bad thing right now as long as it doesn't get strong and get into the warm phases 5 and 6.Typical Nino would keep it out of the warm phases into winter.

 

 

 

 

[John1122]

Euro very similar to last night, snow line is about 50 miles south of last night, basically lined up along 40. North Knox 4 inches, South Knox 1/2 inch. North Davidson 3-4 inches, south Davidson 1-2 inches. The snowline raises as you go west, as follows basically what I described earlier this year as what I meant when I say north of 40 vs South of 40. As you get towards West Tennessee 40 turns SW and moderate snow accumulations are north of Jackson by about 30 miles on that run. Northern Plateau to Mountain City 8-12 inches. Things get rolling Friday evening in NW Tennessee and quickly spread across the state in the overnight hours Friday. By 5/6am Saturday morning heavy snow is falling from Dyersburg to Johnson City with the heavy snow extending well south of 40 along the Plateau. Heavy rain/snow mix (likely one or the other) is falling from Nashville to Knoxville. If we get the evening/overnight timing plus the Euro's slightly colder profiles to keep it up, we may be in business. We will see how much further along we can get until a model blinks.

[jaxjagman]

7 minutes ago, John1122 said:

Euro very similar to last night, snow line is about 50 miles south of last night, basically lined up along 40. North Knox 4 inches, South Knox 1/2 inch. North Davidson 3-4 inches, south Davidson 1-2 inches. The snowline raises as you go west, as follows basically what I described earlier this year as what I meant when I say north of 40 vs South of 40. As you get towards West Tennessee 40 turns SW and moderate snow accumulations are north of Jackson by about 30 miles on that run. Northern Plateau to Mountain City 8-12 inches. Things get rolling Friday evening in NW Tennessee and quickly spread across the state in the overnight hours Friday. By 5/6am Saturday morning heavy snow is falling from Dyersburg to Johnson City with the heavy snow extending well south of 40 along the Plateau. Heavy rain/snow mix (likely one or the other) is falling from Nashville to Knoxville. If we get the evening/overnight timing plus the Euro's slightly colder profiles to keep it up, we may be in business. We will see how much further along we can get until a model blinks.

Nice to see the Euro show something,The HP north of the Valley is gonna be a big player like you mentioned a day or two ago

[jaxjagman]

Still looks like a big CAD into the NC,big ice threat for the sub forum

[jaxjagman]

Yeah the Euro would be nasty for the sub,frozen liquid around 1.5..ouch

[jaxjagman]

To clarify what the Euro is showing would be frozen 1.5"...nasty

 

Edit:Maybe i'm wrong also,the temp profiles would surely support more snow than ice

[BlunderStorm]

I'm loving tonight's Euro ensemble members!

[weathertree4u]

1 hour ago, BlunderStorm said:

I'm loving tonight's Euro ensemble members!

You saw those too! Some of them were pretty heavy hitters for the area, especially I-40 north. I would say the greater majority of them were showing at least something next weekend. 

[Holston_River_Rambler]

6z Fv3 and GFS are now taking the low road alongside the Euro. EPS and GEFS are pretty close at hour 144 with the surface High and Low. Part of their agreement this AM seems to lie in how they are handling the follow up Pacific energy.

As others pointed out overnight the CMC went from low road yesterday to odd Miller B. Looking through its ensembles there is a huge spread in timing and exactly how it is handling the Pacific energy so we may see more ups and downs in CMC runs until it gets the Pac energy figured out. 

6 days is a long lead time for the EPS and GEFS to have figured it out. But if so, I'll take my chances even in Knoxville with that overall setup and let the specifics work themselves out. Is it just me or have the cold air masses been verifying colder?   Maybe the GFS has been slightly too warm: https://imgur.com/a/KmJaTzN  Gif is GFS from last Sunday (as far back as I could go on Tropical Tidbits) 78 hour forecast for the coldest morning of this past week and the trend until verification. (Knoxville actually verified at 21 according to MRX, not the 24 the model seems to show) Looks like our source region for cold air is snow covered as well, from Canada to Nebraska. Maybe too much wish casting and weenie here, but none of above is wrong. 

But I do wonder what the next big difference will be between the models? I just find it hard to believe the main set up is totally worked out.  I suspect that follow up Pacific wave has yet to be totally pegged down and the N. stream energy that tries every few runs or so to drop in and hook up with the main energy will have its say before its said and done.  

[Carvers Gap]

The 0z Euro operational had hp riding along with it.  That was a really nice run.  Each of its last five runs has brought the snow southward as John pointed out.  Beware of the FV3 GFS in one regard(I like the model BTW).  I think it has some errors in its snow map or with its frozen precip maps.  Back to the storm, biggest thing is whether or not a parent high will be in place over the top.  I think that is what is in question.  If it is, plenty of frozen options are on the table.  If not, it may cut or have some sort of energy transfer from the TN Valley to the coastal plain.  I think this far out pretty much everything is on the table.  I have seen tiny vortices in the northern stream change entire predicted storm tracks within the last 48 hours.  Some model solutions have a hp out front and a trailing hp behind the developing slp.  If those ares of hp stay connected, the storm system looks good.   You get a nice banana shaped area of high pressure over the top of the storm.  If not, the storm tries to cut between the two.  We are also entering the time frame where entire model suites can lose a storm only to have it come back in a few days.  I don't think that happens with this one, but it could.  The 0z GEFS ensemble was very good.  6z was not as much.  Plenty of wobbling and maybe even wholesale changes to go.  But the longer this stays in play, obviously the more we have to talk about in a couple of days.  

[AMZ8990]

12Z GFS with some good developments out to HR144.  2m temps in Memphis go from 37 to 33 from hour 132 too 144.  LP tracking right around the coast of New Orleans at 144 with the HP to our north over Wisconsin.  ZR stars to cover west tn at 144 as well.  By 150 the Rain snow line is right around Jackson to, but a good portion of central and northern Arkansas is seeing good snow at this time along with Jackson tn and it’s northern neighbors.  By 162 the LP is off of the coast of Panama City, then the low pushes up the east coast and bombs the mountains of Northeast TN and eastern NC. North western SC gets in on the action too.

[Carvers Gap]

3 minutes ago, AMZ8990 said:

12Z GFS with some good developments out to HR144.  2m temps in Memphis go from 37 to 33 from hour 132 too 144.  LP tracking right around the coast of New Orleans at 144 with the HP to our north over Wisconsin.  ZR stars to cover west tn at 144 as well.  By 150 the Rain snow line is right around Jackson to, but a good portion of central and northern Arkansas is seeing good snow at this time along with Jackson tn and it’s northern neighbors.  By 162 the LP is off of the coast of Panama City, then the low pushes up the east coast and bombs the mountains of Northeast TN and eastern NC. North western SC gets in on the action too.

Much better placement and strength of the parent high pressure.  That is the money track for portions of east central and northeast TN, northern sections of the Plateau, SE KY, and SW VA.  We have more ways up here to lower snowfall totals than most imagine.  Check out what the downslope does to the foothills communities of E TN and (the opposite) what it does to the southeast facing slopes of the Plateau and SW VA/SE KY. I think I saw 23" over the SE KY/SW VA border.  

[1234snow]

The 12z GFS clown: Coming into agreement with last night’s 0z Euro.

[Carvers Gap]

That run is a classic example of my favorite track for NE TN.  Absolutely no idea if this verifies...so everyone please understand that.   But for discussion purposes...

The slp slides by w a good, strong HP over the top.  As the slp slides by and turns NE, it draws in the cold from the hp.  That track is slightly east from a truly, perfect track.  But that is close.  Those types of systems are very tough to forecast in terms of snow.  It is often very tough to know exactly when the valleys switch over and how much precip is left when the switch occurs.  But that is a big dog track...and still a long way to go.  I don't have a ton of confidence, because I have seen these great tracks go to pot as the event gets closer.  But man, who doesn't get just a little bit excited when seeing a map like 1234 just posted!?  

[AMZ8990]

6 minutes ago, Carvers Gap said:

Much better placement and strength of the parent high pressure.  That is the money track for portions of east central and northeast TN, northern sections of the Plateau, SE KY, and SW VA.  We have more ways up here to lower snowfall totals than most imagine.  Check out what the downslope does to the foothills communities of E TN and (the opposite) what it does to the southeast facing slopes of the Plateau and SW VA/SE KY. I think I saw 23" over the SE KY/SW VA border.  

23” is pretty crazy to think about, I could see it happening in those areas you mentioned though.  Did you see some of those numbers in central/northern Arkansas?  They had close to a foot in several areas.  This storm if modeled correctly is massive too.  A lot of states could be impacted theoretically.  Still a long ways to go though.

[AMZ8990]

4 minutes ago, Carvers Gap said:

That run is a classic example of my favorite track for NE TN.  Absolutely no idea if this verifies...so everyone please understand that.   But for discussion purposes...

The slp slides by w a good, strong HP over the top.  As the slp slides by and turns NE, it draws in the cold from the hp.  That track is slightly east from a truly, perfect track.  But that is close.  Those types of systems are very tough to forecast in terms of snow.  It is often very tough to know exactly when the valleys switch over and how much precip is left when the switch occurs.  But that is a big dog track...and still a long way to go.  I don't have a ton of confidence, because I have seen these great tracks go to pot as the event gets closer.  But man, who doesn't get just a little bit excited when seeing a map like 1234 just posted!?  

The guys in the southeastern forum are gonna have a heart attack if these maps continue to pour out these hearstopping snow totals in the CAD areas. Lol.  I’ll be interested to see what the 12z euro holds.

[Carvers Gap]

8 minutes ago, AMZ8990 said:

The guys in the southeastern forum are gonna have a heart attack if these maps continue to pour out these hearstopping snow totals in the CAD areas. Lol.  I’ll be interested to see what the 12z euro holds.

Those maps are about to give me a heart attack!  LOL.  That is my absolute favorite track to follow.  I hope(fingers crossed) that it continues to take the low road.  That and we get strong enough hp over the top.  I am pleased to see the trend of the hp coming back into play...it was absent a couple of days ago.  I remind myself that great solutions come and go at this range.  But yeah, I ain't gonna lie...I like a good clown map.  LOL.

[1234snow]

Like Carver’s said this run was different with the banana high to the north helping to switch the rain over to heavy snow on the north and eastern fringes of our area. That is something different from the past several runs of the GFS. Euro has been more of a front end thump and then switching to rain at the end.

I would be shocked to see the models lose this storm just based on the consistency of all models seeing the energy out west and rolling it east. That’s a fairly big trough ejecting out of the 4 corners region.

What I have noticed is that the system has trended slower the past few days of runs. That has me concerned a little bit. I’m afraid the energy will hang back longer out west and we will lose our cold air source and highs to the north and we will be stuck with a cold rain.

Regardless I’ll file that run into my top 5 fantasy runs ever lol.

[Carvers Gap]

1 minute ago, 1234snow said:

Like Carver’s said this run was different with the banana high to the north helping to switch the rain over to heavy snow on the north and eastern fringes of our area. That is something different from the past several runs of the GFS. Euro has been more of a front end thump and then switching to rain at the end.

I would be shocked to see the models lose this storm just based on the consistency of all models seeing the energy out west and rolling it east. That’s a fairly big trough ejecting out of the 4 corners region.

What I have noticed is that the system has trended slower the past few days of runs. That has me concerned a little bit. I’m afraid the energy will hang back longer out west and we will lose our cold air source and highs to the north and we will be stuck with a cold rain.

Regardless I’ll file that run into my top 5 fantasy runs ever lol.

Good post.

Yeah, this one doesn't seem to be the kind to get lost in the shuffle.  But I could see it becoming a weak wave over the next few days only for it to strengthen again as the time gets closer.  I think the energy and timing is there for a storm.  Also, how the trough interacts w the northern stream is important.  How strong does the northern stream get?  

I can't decide on the speed being good or bad.  On some of the slower runs, I notice that they can have the high over the top w maybe a little less banana high.  Faster runs sometimes get in between two highs and send energy up west  of the Valley.  It would be nice if those two highs(seen on several runs) would hook-up and form a banana hp over the top.  

Still, great to be able to track a storm this early in the season.  At six days to go, we will probably see all kinds of slp track movement.  But we will take our 12z GFS run and put it up on the virtual mantle for a while.  LOL.

[BlunderStorm]

30 minutes ago, 1234snow said:

The 12z GFS clown: Coming into agreement with last night’s 0z Euro.

Oh Snap! That is a VERY heavy wet snow... look at the bullseye around the Lee, Harlan, Wise area. That would be pretty devastating to the power lines. It reminds me of December 18, 2009. Only one run a week out but still interesting.

 

[1234snow]

12z Canadian has a similar idea and track as the GFS but it is warmer. West TN gets heavy snow on the backside. 12”+ west of Nashville.

Canadian does have an initial strip of snow across most of the state on Saturday before the main event that drops a few inches.

ICON is by far the warmest model with rain even in CAD regions east of the mountains

[TellicoWx]

12z GEFS looks good for the mean and individual members, especially for you guys in NE. 

[Holston_River_Rambler]

12z UKMET as far out as I have access to it:

[TellicoWx]

12z GEFS mean:

[Carvers Gap]

The FV3...welp.  

[Carvers Gap]

Those snow maps have to have an issue w the algorithm.  But algorithm or not, the FV3 tracks is a nice one.

[TellicoWx]

3 minutes ago, Carvers Gap said:

Those snow maps have to have an issue w the algorithm.  But algorithm or not, the FV3 tracks is a nice one.

Same with the mean SLP track on the GEFS, right along the gulf coast to Charleston

[TellicoWx]

Wow, just actually looked at FV3 op...lmao. Social media is gonna explode on that one.

[TellicoWx]

It is definitely the algorithm on tropical tidbits. TT (top), Dupage (bottom).