Spring/Summer 2018 Mid to Long Term Discussion.

[John1122]

40 minutes ago, tnweathernut said:

This would be the second opportunity to discuss snow in the spring/summer thread.  Even though unlikely....... the pattern says it’s not impossible.

The crazy thing is that it follows that with a Plateau/North Central Valley ice storm 24 hours later as waves of moisture work along a stalled but strong Arctic boundary. I would say stranger things have happened, but I'm not sure they actually have. We did get 12 inches of snow in April of 1987 and 9 inches here in May around 100 years ago when my grandfather was a teenager and said the snow laid flat knee high corn. The Canadian has the same system with the boundary stalled a little further north and the northern half of Kentucky gets a big ice event.

[Holston_River_Rambler]

The highs I noticed several days ago still look like they're trying to come down and as y'all noted... them getting far enough south to produce a bit of wintry weather isn't  impossible. I still suspect that once those highs deliver their cold anomalies somewhere in the US, that's the end and the N. Hemisphere will have sobered up. Currently the coldest 850 anomalies in the N. Hemisphere are over W Canada and just don't think there can be a reloading. This new -NAO that the current storm is helping along slows the 500mb flow, and it's effects eventually bring the highs down. Not that I want them at this point, (ok maybe a little if they can push the boundary south of the TN Valley) more trying to figure out when we finally shake all this and get into some consistently warmer weather. 

In the meantime though this week the SE ridge seems to have verified stronger than models had forecast. What looked to be a very wet and gloomy week in the eastern valley a week or so ago has ended up gloomy, but not so wet. The flow has been more SW - NE and so western forum areas have gotten more rain as the boundary has pushed NW.  Is this a trend for how the boundary might set up for the future threats or does the current storm shake things up for the next couple of weeks as it kicks out the bigger cyclone in the Atlantic? Crankyweatherguy (I think a good follow for understanding large-scale hemispheric patterns) on twitter points out there is still plenty of snowpack in Canada for these highs to build on. Does this impact how far south the highs can make it in April? How does the energy end up timing with these highs? 

Looks like I should have followed my own advice in tracking. Never the first, since the "April Fool's" Storm is living up to its name. Not that I ever expected much out of it aside from hopefully a good track analog for a colder season.  But I was looking at it as the last in the line of the nor'easters that came from the Strat driven -NAO, but now I think it is the first to help create a new, more typical -NAO.  At least it's pulling the boundary through for a day or two for a break in the gloom!  I speculate that the April 10 - 13 period has some legs for a storm in the E US. As to what that means a this range, who's to say?  GFS keeps wanting to pop a large cyclone and although the details bounce around, it keeps showing up.  Does it take a lower track after some previous disturbances carve out the trough?  Is it the coveted "transition storm" in this case for a warmer pattern? 

I leave you with a crankyweatherguy image (taken from http://www.stormhamster.com/entry/e032818.htm). That zonal yellow flow upstream looks mighty nice to me. 

[Carvers Gap]

I have my doubts considering we are basically talking about a snow mean for the first half of April!  Anyway, here is the 16 day snow mean from the 18z GEFS.  I truly doubt it verifies, but this is for posterity.  Someday, when we are old geezers, we can say that we used to track snowstorms well into April back in the day. Weeklies....mainly cold w some moderation and then cold again.  Viva la spring?  Not often you get a 1-3" snow mean over a sizable portions of the forum area for April.  

 

[Carvers Gap]

Have to think that the Canadian solution is about as far south as this can make it....and that it is more likely to see this system work north over time until it gets to northern KY or the Ohio river.  Mountain snow and cold valley rain is likely.

[John1122]

The Euro control snow map is similar area but much heavier snow depth to the GFS mean map above. 3-6 inches across a lot of the northern half of Tennessee/Southern Ky. Canadian still has 1-3 inch snows in the northern part of East Tennessee from the Plateau eastward. Not quite the monster from 00z Friday but it worked it's way back well south with the snow shield.

[John1122]

Getting to the 5.5 day point now and the Euro, GFS and Canadian still have a major winter event for the forum area. This storm is being depicted from Northern Kentucky to the Southern Tn border areas over the last few days. So everyone in that window may have skin in the game still. This has shown up on the Canadian suite, the European suite and the American suite over the past several days in some form. I won't post the Euro map, but it's very similar to the GFS but heavier in the Mountains and NC. What a crazy year this will have been if this comes to pass. The Euro Control is 2-4 from Nashville to Crossville, 4-6 along and north of 40 in Eastern areas.

Canadian

[John1122]

JKL mentions snow, especially for their southern tier of counties due to the Euro and GFS runs taking the ULL further south. MRX doesn't mention it at all.

[Holston_River_Rambler]

I think I was wrong about 10th - 13th period and this storm (the one John is posting about) is the transition storm.  Like the "April Fool's" one that came through about 3 days earlier than the longer range models had been showing, I think this one will too (by this I mean a few days earlier than my prediction last week for 10th - 13th, NOT earlier than the 7 - 8th).

Not that there isn't still a bigger storm showing up then (10-13), but everything is pushed well north as a big wave in the Pac jet races in.  I guess if we are still in a Nina with N. stream/ faster flow dominating this makes sense. Looks like my 10th-13th period may now be one for thunderstorm folks! 

This snow potential looks interesting to me in that CMC, GFS, and Euro show northern energy elongating as it races out from the great lakes towards maritime Canada and suppressing the flow. Suppression is probably a great thing in April. I feel like you'd want a super dynamic, wound up system to give you snow in April, but I guess it's possible with other means.  The energy with this is much more apparent to me at 300 mb which seems odd too. Normally you'd see a vort at 500 mb, but it's barely visible there. Looking through EPS members, a majority favor a more northern solution, but quite a few like a favorable track for us and one even suppresses the whole thing all the way to coastal SC. 

 

[Carvers Gap]

We want this south of us and let it come back north...these spring storms almost always come back north.  Has been a reliable trend this spring and for most springs.  It really, really does not want to snow at this time of year....but if nature was throwing strikes, this one is trying to clip the high, outside corner.  This storm is on the 0z/6z GFS, 0z CMC, 0z Euro, 0z GEFS, w the EPS still very light(but increased).  Absolutely any snow is bonus snow from this point onward.  

[John1122]

The Canadian and GFS ticked north at 12z and the Euro went a little bit south or maintained. Basically a strip of 2-4 inches along the path of the upper low as it swoops across the area. Pretty much a stripe right down the middle, east to west on the Euro with heavier totals as you move eastward. The stripe of heavier snow is about 3 counties wide north to south, also expanding as you work eastward. 

All the models seem to agree on the system and that it will produce wintry precip, but they will have to work a while on the track. Looks like the Central Kentucky to Central Tennessee are in the window on the 12z suite.

[Carvers Gap]

MRX w/ a small comment on the early April event later this week...Pretty brave.  I am not sure I would have had the courage to mention snow, even though the models indicated that there is some evidence to support it.  12z Euro had the snow axis in the same spot.  The EPS had 2" of snow for NE TN.  Surreal.

Another front should move through Friday,
then a wave may form on the front and keep significant chances for
precipitation going through Saturday. Models indicate it may be cold
enough for the rain to mix with snow later Friday night/early
Saturday across northern areas especially higher terrain. Sunday
looks to be between systems so should be drier, then another frontal
system is forecast to approach by Monday.

[John1122]

The EPS  individual members were impressive. A large number had pretty big events in the region. The Euro itself is probably on the southern edge of it's ensembles by the look of big hitters for the northern half of Tennessee and into Kentucky. There were big hitters in there for everyone though. Crazy that we're in the 5 day range with all major modeling and ens showing a winter event for April 7th-8th.

[Carvers Gap]

The 240 hour nationwide, snow total maps on both the CMC and the GFS are crazy for April.  They look like the dead of winter.  As expected the GFS has ticked north with each run though the 12z CMC is now straddling the TN/KY border w 5" snow totals.   What is crazy....I am not sure that is the last threat as it gets very cold.  Would not be surprised to see snow flurries in the Valley and accumulations in the mountains at some point this month - maybe on multiple occasions.  This is putting a serious glitch in my spring fishing.  I was planning on going this weekend...but cold rain and 40ish temps may stop that.  

[John1122]

The Euro has snow down to 40. With 1-3 inches accord to what side of the KY/TN line you are on. The GFS is a little further north. The Canadian was a big hitter north of 40. Track and time of day still to be determined but I still think 40 north to the Ohio River is in the window and somewhere in there will be a 100 mile or so wide strip of heavy wet snow.  

[Holston_River_Rambler]

One thing I noticed this morning with the end of the 6z NAM run (I know, but hear me out) is that it is trying to develop a second low that looks like it might want to run more up the coast (in a SW-NE direction) at the end of this weekend system.  I was trying to figure out why and the answer seems to be it has a stronger jet streak at 250mb over the midwest helping buckle the trough.  The GFS and GEFS had been trending to a sharper trough as well, but backed off at 6z. The Euro and CMC have been trending that way too. Sometimes I think the NAM is good and hinting at changes although like a pendulum, the NAM runs can swing widely and the end seems to be somewhere in the middle. I looked at the EPS member snow swaths to see if any showed a more SW - NW trajectory. Maybe 2 did. The rest were pretty W - E which would indicate a more "slider" type solution and the vast majority were north, but a notable few get Blunderstorm and Kentucky in on the fun. Bottom line: this could be a whole lot of nothing, even though all the models seem to want to show the low sliding into the TN valley as of now (a likely solution given the pattern this year), I'm not quite sure we've seen the final solution to all this yet. 

EDIT: WPC Winter Wx probabilities for day 4 are optimistic for northern areas

Also: starting to think I shouldn't have been so quick to back off on my ~10 -13th period for a big, pattern changing cyclone.  GFS, EURO, CMC all now show another coastal (for NE) and then a big cut off low in the midwest.  

[John1122]

Getting NAM'd? This would be impressive.  I don't know how much would actually manage to accumulate in Eastern areas as it falls between 8 am and 2pm. It's just so hard to get accumulation during the day this time of year. The legendary April of 87 event started a couple hours before sunset and went overnight if I recall correctly. The GFS is more central Kentucky storm and there's another one on it's heels for Kentucky on the GFS.  Even though we're getting close to the event,  the modeled track appears to potentially effect anywhere from the Tennessee state line with the gulf states all the way to the Ohio river. Somewhere in that area should see heavy snow falling at the very least, better sticking the further north you are obviously and in areas where precip comes at night.

[Kentucky]

Just regained power/internet from last nights storms. For once, I wouldn't care to see this snow miss SE KY. It has every time, so why change now.

[Holston_River_Rambler]

18z, 12k NAM has the second low again and gives a *little* snowy love to Tri-Cities, SWVA, and higher elevations up that way on Sat afternoon.  RGEM has the secondary piece of energy too, and the NAM 3k, but neither of these look as robust. The H5 energy responsible for all this looks to be scooting right along, but turns enough to generate a bit of precip. This thing is indistinct on the models, so I wonder if it has any more surprises in store as it gets closer. Safe to day though that as of now, as other have pointed out above, probably not good that it comes through during prime day time heating. 

Also interesting that the Hi-Res models show a potent squall line in MS and LA.  Almost has a Mesoscale Convective (C or S) look to it, but not sure on the definitions for those.  If that is the case wonder how that impacts the secondary system if at all?

[BlunderStorm]

Support for snow in the Tennessee Valley has went up across the board tonight as of the 0z runs especially for me. The GFS, CMC, EURO, 3km NAM, RGEM, HRDPS, and ICON all seem to show more snow. My understanding is very limited but a common thing all the models seemingly agree on is a more robust back end to the system or at least that is what I could gather from my untrained eye. Perhaps you all could elaborate more?

[John1122]

I'd be more excited if this were coming through at 8pm to 4am instead of 8am to 4pm. Still the models are generally showing some very heavy snow rates developing across the area. The Euro snow accumulation map shows .5 to 1.5 inch totals for non elevated areas north of 40 and even more in SWVA and Kentucky. That would take really heavy snow falling to get it to stick. It will be aided a little in some areas by the relative cold of the past few days. I was 27 degrees yesterday morning and I'm in the 30s and dropping as we speak. Every little bit helps. As always, northern areas and above 2500-3000 feet are likely to do the best. Everywhere else, if we can get snow in the air, it's a win.

[Holston_River_Rambler]

I'm with John.  This is coming though at the worst possible time of day, but just seeing some snow falling is cool in April.  As John says northern areas and elevation, but unlike a lot of the systems this year this one on Saturday afternoon looks like a Miller A so Blunderstorm (if everything plays out well) you should only have to deal with normal daytime heating issues and no valley warm nose.  I'd say you are the best situated of us all. 

Also of interest: looking at the Hi-Res models there is a distinct backdoor front dropping down through VA and NC.  Normally there is some cold air damming with these storms, but this front looks pretty stout in that it is visible on simulated radar. If that can make it to your location Blunderstorm it might give you some enhancement, but unfortunately I bet it stops at that Wytheville/ Marion cutoff we've talked about. The NAM Nest actually shows it making it to Blountville, TN. Either way should be fun to watch on radar. 

There have been some changes in the system for Monday/ Tuesday as well. The GFS has been trending to emphasize the second piece of energy that is dropping further south.  I think we've yet to see all the surprises that one has too.  I say let's get this one through and then see what the next one will do.  After that, sunshine and warmth I hope.  I know I may have seemed down on the snow lately, so apologies, but I needed a break with a bit of sun and warmth. I've had a little break and am ready for one last hurrah. 

[Carvers Gap]

Looks like NE TN and SW VA now could see snow (potentially falling after dark) unless I am misreading the times.  I am always suspicious of snow modeled in April...but yet, there it is.  IMHO, usually snow at this time of year will fall in a narrow band.  Within that band there can be surprises.  I am not quite ready to unleash that as a serious idea for TRI.  The models ticked south overnight and have trended that way slightly with each of the last few runs(which runs counter to my original thinking).  Now, do I think it will eventually move back north.  I don't know now.  With the event getting closer, it is possible that the modeling is now catching "real" trends...but I still suspect a move north as a final verification.  Nevertheless on April 6th...I will now be watching the 12z suite to see if MBY will get snow tomorrow.  @BlunderStorm, this would mark the seventh straight month of a trace or more, right?  That is far more commentary than I originally meant to add...thanks to everyone for their discussion. 

[Carvers Gap]

Total amounts on the 6z GFS through about 48(sorry, I cut off the hour)....then SW VA has another system that pulls through after this.   I share the skepticism of everyone above...and yet, there it is.  LOL.  I also attached the Euro operational.  Might as well track it...even if it is gone at 12z.  Again, I am not sure this is the last one of these either.  Like flash said, any snow is bonus snow.  Even one flake.

[Holston_River_Rambler]

I'm thinking about scooting up to Hensley Settlement in Cumberland Gap NP tomorrow afternoon. Should be right at 3000 feet. Will wait to see what the trends are today though to decide. 

 

 

[Stovepipe]

I can take or leave the snow but I'm more concerned about the temps.  If we dip down much below 30 I'm gonna have to winterize the camper.  I really don't want to do that.  Glad I didn't try to get cute with the garden this year and plant a bunch of stuff early.  Thankfully only cool season stuff in the ground at the moment.

Current SREF mean of 27 degrees for TYS... ugh.

[John1122]

My current forecast calls for a mixed bag of rain/sleet/snow for tomorrow with a high of 36 degrees. What a crazy spring! I figured it would be either snow or rain, surprised sleet is working it's way into the equation. You rarely see it outside the winter months in my experience.

[John1122]

The NAM and especially NAM3K are pretty aggressive at 18z. 1-3 inches falling north of 40 with some higher pockets in NE areas. Don't know if that will happen and doubt even 1/2 of that will accumulate but spring has shocked me so far. It may again.

[1234snow]

The NAM and especially NAM3K are pretty aggressive at 18z. 1-3 inches falling north of 40 with some higher pockets in NE areas. Don't know if that will happen and doubt even 1/2 of that will accumulate but spring has shocked me so far. It may again.

I have a feeling we might be getting NAM’d again. All other models are skimpy on backside development. The normally reliable RGEM didn’t have much on the backside. But the RGEM looked funky with convection in the Gulf Coast that may rob moisture up this way. Anyways it would just be cool to see big flakes falling this late!

[jaxjagman]

36 minutes ago, 1234snow said:

 

I have a feeling we might be getting NAM’d again. All other models are skimpy on backside development. The normally reliable RGEM didn’t have much on the backside. But the RGEM looked funky with convection in the Gulf Coast that may rob moisture up this way. Anyways it would just be cool to see big flakes falling this late!

 

Maybe,short range models aren't coming in very well.Maybe this run will cycle better

[BlunderStorm]

3 hours ago, 1234snow said:

 

I have a feeling we might be getting NAM’d again. All other models are skimpy on backside development. The normally reliable RGEM didn’t have much on the backside. But the RGEM looked funky with convection in the Gulf Coast that may rob moisture up this way. Anyways it would just be cool to see big flakes falling this late!

 

Yep we just got NAM'd big time. You can really see the drastic drop between 18z and 0z. EDIT: On a 2nd note the RGEM and ICON up the snow totals a little.