2016-2017 Great Tennessee Valley Winter Discussion

[JayCee]

One thing is certain through December--the Great Lakes are open for business.  The U.S. has been so warm this fall--and warm late--that the Lakes are completely unfrozen and unusually warm.  Folks living in the snow belts around the lakes will be getting buried with all the intense cold shots coming over them the next few weeks.  I'd like to experience a lake effect snow storm just once in my life. 

[JayCee]

10 hours ago, John1122 said:

Wow, that run of the GFS gives East Tennessee 14-16 inches of rain topped off by a major ice storm from the Plateau west. 

They can keep the cold out west if it means an ice storm.  I'm a patient man.  I'll wait for the deeper cold to arrive later for my snow.

And while we are still in a drought, that much rain would be a disaster for the burned areas in and around Gatlinburg. 

[Coach B]

9 minutes ago, JayCee said:

Folks living in the snow belts around the lakes will be getting buried with all the intense cold shots coming over them the next few weeks.  I'd like to experience a lake effect snow storm just once in my life. 

I would love to snow chase a lake effect event either in the Tug Hill Plateau or along the Chautauqua Ridge in NY. Lord willing if I make it to retirement healthy and able enough its on my short list of things to do. Not sure the wife would be real excited it about it. She's already complaining about the cold daily. 

[nrgjeff]

Thank you. Sometimes it's better to be lucky than good, lol. But yes I agree with the solution.

15 hours ago, Carvers Gap said:

Jeff, those weeklies look exactly like your last post.   You are a ninja.  Minus a ten day break, they are pretty cold at 850 and the 500 mb pattern looks very good weeks 1-2 and 4-6.5.  Trough is centered in the East after d28-46.  Looks like a -EPO and -NAO to boot in January.  Cold over the Plains, especially northern.  SE has to fight the SER which isn't all bad w blocking.  Couldn't ask for a much better look this far out.  

First in the mid-term, a warm rain event or even severe wx Deep South would not surprise me the weekend of December 17. Trough is positive and coming on the heels of the Day 7-8 cold so I really doubt severe trouble in the immediate Valley.

I still like evolution to a colder pattern. Bering Sea ridge has a particularly good correlation with multi-week cold patterns. Some research shows even better than the PNA, and that is saying something because the PNA has a correlation max over the Southeast US. Bering Sea ridge will take time, no doubt, as cold spills out West first. The parent trough should come east in following weeks.

At least some of that dense cold in the Upper Midwest will spill down here, but that could spell ice - ugly! Rather get the parent trough in here. Delay is not a bad thing, perhaps a blessing in disguise. Get the cold pattern to drop into the South deeper into meteorological winter, and it should pay dividends for snow lovers. By either way, or both, odds are good for a cold pattern to develop here.

Regardless, with that baroclinicity and an active jet stream the weather will be interesting. Worst case is some severe weather. Best case is multiple snows. Everything in between is on the table. Cannot really find a boring outcome the next few weeks. Buckle up and enjoy!

[JayCee]

1 hour ago, nrgjeff said:

Thank you. Sometimes it's better to be lucky than good, lol. But yes I agree with the solution.

First in the mid-term, a warm rain event or even severe wx Deep South would not surprise me the weekend of December 17. Trough is positive and coming on the heels of the Day 7-8 cold so I really doubt severe trouble in the immediate Valley.

I still like evolution to a colder pattern. Bering Sea ridge has a particularly good correlation with multi-week cold patterns. Some research shows even better than the PNA, and that is saying something because the PNA has a correlation max over the Southeast US. Bering Sea ridge will take time, no doubt, as cold spills out West first. The parent trough should come east in following weeks.

At least some of that dense cold in the Upper Midwest will spill down here, but that could spell ice - ugly! Rather get the parent trough in here. Delay is not a bad thing, perhaps a blessing in disguise. Get the cold pattern to drop into the South deeper into meteorological winter, and it should pay dividends for snow lovers. By either way, or both, odds are good for a cold pattern to develop here.

Regardless, with that baroclinicity and an active jet stream the weather will be interesting. Worst case is some severe weather. Best case is multiple snows. Everything in between is on the table. Cannot really find a boring outcome the next few weeks. Buckle up and enjoy!

Thanks for the info and insight.  After 3 months of basically nothing--not even rain or thunderstorms--I'm ready for something to track.

[Carvers Gap]

I am going to insert a URL link to Tropical Tidbits for the 6z para GFS.  It had slider followed by an ice storm...

[JayCee]

1 hour ago, Coach B said:

I would love to snow chase a lake effect event either in the Tug Hill Plateau or along the Chautauqua Ridge in NY. Lord willing if I make it to retirement healthy and able enough its on my short list of things to do. Not sure the wife would be real excited it about it. She's already complaining about the cold daily. 

LOL...yes, everyone I work with is already complaining, and this is the FIRST real cold snap.  I tell 'em buckle up for a long winter ahead.  Just hope I'm right.

[Carvers Gap]

12z GFS was close to something.  The CMC has a decent front-end thump for the NE corner of the forum at 222.  Then, a monster CAD event on the other side of the Apps.  The 6z GFS para from my earlier post has the ice storm that the CMC has.

[JayCee]

2 hours ago, Carvers Gap said:

12z GFS was close to something.  The CMC has a decent front-end thump for the NE corner of the forum at 222.  Then, a monster CAD event on the other side of the Apps.  The 6z GFS para from my earlier post has the ice storm that the CMC has.

They say nature always balances stuff out.  We’ve had a very long stretch of little weather to speak of.  Perhaps the pendulum is swinging to the wild side now.  We could be in for some pretty extreme weather events over the winter months.

[1234snow]

Quick glance at the 18z GFS and it looked better then the 12z. The mid week system is a little colder next week and the cold locks in up to 240 hours.

[jaxjagman]

Who's right Day 7 ?..lol

[jaxjagman]

Prognostic Discussion for Experimental Week 3-4 Outlook 
NWS Climate Prediction Center College Park MD 
300PM EST Fri Dec 09 2016 

Week 3-4 Forecast Discussion Valid Sat Dec 24 2016-Fri Jan 06 2017 

There are some conflicting signals among the various forecast tools during the week 3-4 period. The various dynamical model forecasts show large differences, with the CFS continuing to predict below-normal temperatures for much of Canada, while the ECMWF and JMA models indicate relatively warm temperatures for much of North America. Available models are predicting an amplified circulation pattern during the week 2 period, indicating a trough over western North America and a ridge over the eastern CONUS. The CFS week 3-4 forecast indicates persistence of major circulation anomalies over the region into week 3, while the ECMWF and JMA ensemble means predict a westward retrogression of the trough in the west leading to rising 500-hPa heights over the western CONUS in both models. 

Tropical circulation and OLR anomalies project very weakly on the MJO RMM index, though some model forecasts suggest a possible emergence of the subseasonal convective signal over the Western Hemisphere or West Pacific in the next several weeks. The latest weekly average sea surface temperature of the Nino 3.4 region is -0.4 degrees Celsius, with weak La Nina conditions apparent for the equatorial Pacific Ocean and overlying atmosphere. Statistical temperature and precipitation forecasts based on regression to climate indices generally depicts a weak La Nina pattern over North America, influenced by decadal trends. 

As the JMA forecast for week 3 and 4 is somewhat different from both the CFS and ECMWF forecasts and from the predicted week 2 circulation pattern, the week 3-4 outlook relies mostly on the model forecasts from the ECMWF and CFS ensemble prediction systems. As the ECMWF and CFS circulation patterns forecast for week 4 alone have only weak anomalies over the CONUS, the week 3-4 outlook also relies primarily on temperature and precipitation forecasts from these ensemble prediction systems for week 3. The forecast circulation pattern from a blend of the CFS and ECMWF models indicates anomalous troughing centered in western Canada near the Alaska Panhandle with anomalous ridging centered over Quebec northeast of the Great Lakes. 

The surface temperature outlook is constructed primarily using a blend of probability forecasts based on the CFS and ECMWF ensembles, with adjustments based on skill-calibrated dynamical model probability forecasts. Continuity with the week-2 forecast and the week 3-4 outlook issued last week is also considered. The CFS temperature forecast is somewhat more consistent with a canonical La Nina circulation pattern than the ECMWF, indicating a greater likelihood of below normal temperatures for parts of the Pacific Northwest and Northern Plains. The outlook indicates substantial warming between week 2 and week 3 for the southern tier including the Southwest CONUS northward into the Central Rockies, the Central and Southern Plains, and the Southeast CONUS northward into the Ohio Valley and Mid-Atlantic regions. The highest probabilities for above-normal temperatures are indicated in the Southwest. A greater likelihood of below-normal temperatures continues for southeastern Alaska and parts of the Pacific Northwest and Northern Plains. 

The precipitation outlook primarily relies on a blend of the CFS and ECMWF ensemble model forecasts for week 3 with some adjustments of probabilities based on the correlation-weighted blend of calibrated model output for weeks 3 and 4. The outlook is roughly consistent with weak La Nina conditions. Above-median precipitation is more likely over the Alaska Panhandle and parts of the Pacific Northwest, and from the Tennessee and Ohio Valleys into the Mid-Atlantic, while below-median precipitation is more likely over much of the southern tier of the CONUS, with highest probabilities near the border with Mexico. Anomalous northerly mid-level flow is predicted by model forecasts over Alaska, such that below-median precipitation is more likely over much of interior of the state. 

Hawaii is forecast to have slightly enhanced chances of above-normal temperatures due to weak positive sea surface temperature anomalies in its vicinity. Model forecasts indicate an increased likelihood of below-median precipitation for Hawaii. 
 

 

[John1122]

Details are all over the place but two things seem to be established, cold air will at least be close by if not over us and there's going to be a lot of storms. No specific details are otherwise clear at all. The 0z Canadian is a mega-ice storm in a week. The GFS is sightly warmer with the ice storm being in Kentucky mainly. On the Canadian the storm winds up and shoves a high out of the Ohio Valley to the NE and it cuts in the same direction the high leaves but not before dumping a lot of ice across the Valley. On the GFS it starts out south west of a 1040 high, that is centered  in the Dakotas. The high doesn't move east over the storm which normally happens, it supresses the storm perfectly into Northern Texas. Which is normally a great track for us. But the High suddenly races due south and kicks the storm NE and turns it into a cutter.

[John1122]

Canadian ice storm map.

 

[jaxjagman]

Nice dynamical system,that's one heck of a line both the GFS and Euro show,just timing differences.Tornado threat looks more at this time towards the SW parts of the Valley and deeper south,looks like the DP's could hit the upper 60's here in the SW Valley.But who knows,the models could change again but the GFS surely caved to the Euro.

 

[JayCee]

5 hours ago, John1122 said:

Canadian ice storm map.

 

 

That would be pretty unusual for the Lower Ohio and Tennessee Valleys.  I remember many destructive ice storms in January and February, but I don't believe I can remember one like that so early in the winter season (December).

[Carvers Gap]

In light of some good overnight work by John, Jax, and crew...I encourage everyone to read page one of this thread and think about where this pattern is at the moment.  I think it shows some pretty high quality discussion (as early as August) about this winter.  The Nina thread has some good disco as well.  Strong work by the forum.

[JayCee]

6 minutes ago, Carvers Gap said:

In light of some good overnight work by John, Jax, and crew...I encourage everyone to read page one of this thread and think about where this pattern is at the moment.  I think it shows some pretty high quality discussion (as early as August) about this winter.  The Nina thread has some good disco as well.  Strong work by the forum.

Agreed.  The information provided by those you mentioned is exceptional.  John is a walking weather history book and almanac.  I'm from London, KY originally, so I remember many of the storms he mentioned earlier in this thread.  Both areas usually have similar winter weather during major events. 

I come here often to check on what is being posted, because I've come to see it as a reliable source of information and opinions of what's developing.  I appreciate all the work that's done here. 

[nrgjeff]

CPC is going conservative as usual. Why make a call if you don't have to do so? Meanwhile in the real world outside academia and government...

If the MJO convection really does come out from the Indian Ocean in the the Western Pacific, the Western US cold will come to the Southeast US faster than General Sherman on steroids.

Looking under the hood of the Euro weekly clusters, some very cold solutions are out there. No confidence to say they are right, but EC all over? Come on!

[John1122]

3 hours ago, JayCee said:

 

That would be pretty unusual for the Lower Ohio and Tennessee Valleys.  I remember many destructive ice storms in January and February, but I don't believe I can remember one like that so early in the winter season (December).

I can't say where else in the region it hit, but the biggest ice storm I've ever seen was just before Christmas in the late 1990s. 48 hours of rain and 20s. It was a black Christmas here as a good portion of Campbell Co was without power for the holiday.

[Snowless in Carrollton]

22 minutes ago, John1122 said:

I can't say where else in the region it hit, but the biggest ice storm I've ever seen was just before Christmas in the late 1990s. 48 hours of rain and 20s. It was a black Christmas here as a good portion of Campbell Co was without power for the holiday.

That wasn't the same ice storm that hit Virginia in December 1998 was it ? I have a friend who lived near Richmond and says they were out of power because of all the ice around Christmas 1998.

[jaxjagman]

CMC IS insanely cold in the Valley.1 degree next Monday morning Mid Tn.

[John1122]

2 hours ago, Snowless in Carrollton said:

That wasn't the same ice storm that hit Virginia in December 1998 was it ? I have a friend who lived near Richmond and says they were out of power because of all the ice around Christmas 1998.

Yes, it was Christmas of 1998, I had almost 2 inches of ice. Temp never got above 28 during a long duration rain event.

[JayCee]

46 minutes ago, John1122 said:

Yes, it was Christmas of 1998, I had almost 2 inches of ice. Temp never got above 28 during a long duration rain event.

I do remember a freezing rain event around that time.  I lived in Corbin, KY then...but it wasn't nearly as bad as you had it.  Corbin/London sits around 1,100-1,200 feet, and we we're quite a bit warmer than at your elevation.  I remember everything looking pretty and glazed, but no major damage around.  The freakish snow storm of February 1998 did far more damage.  Heavy wet snow--over a foot--brought down pine trees everywhere.  It was the heaviest wet snow I've ever seen.  And it all fell while temps hovered around 33F.  It was as damaging to trees as any ice storm I've seen.  Our power was out for two days.

[John1122]

This outcome makes absolutely no sense to me. Why would this system cut if everything is as depicted here? The system isn't wound up and that's a fairly strong high north of it.

 

[John1122]

The following panel and outcome also baffle me.  You have that 1046 HP with North winds in our area. The snow/ice pack is along the Ohio Valley at this point.  Temps are in the -10s and -20s just north of the high. Yet temps struggle to even get below freezing for our area in the 24 hours that follow this.

[Carvers Gap]

11 hours ago, JayCee said:

Agreed.  The information provided by those you mentioned is exceptional.  John is a walking weather history book and almanac.  I'm from London, KY originally, so I remember many of the storms he mentioned earlier in this thread.  Both areas usually have similar winter weather during major events. 

I come here often to check on what is being posted, because I've come to see it as a reliable source of information and opinions of what's developing.  I appreciate all the work that's done here. 

Should have included Jeff in that comment as well about great discussion on the first page of this thread.  One of the great things about this site is having folks like Jeff and Mr. Bob who take time to share knowledge from their profession.  

[Carvers Gap]

The 0z CMC depicts colder air that penetrates into the forum area, even the para-GFS does model this as well on its 18z run.  It would appear that there are a few chances for frozen precip, especially west and middle areas.  Timing varies.  As John mentions earlier, how far can these waves move north into hp?  Looks like multiple waves will ride an Arctic front that will sometimes sag across the area and sometimes get pushed north by a SER.  Spacing between waves will help determine if cold air will be in place for the next one.  That may well mean the difference between a frozen solution and a rainy one.  

[Carvers Gap]

[John1122]

The 18z Para has a strong arctic high under cutting the precip aND dumping heavy ice on the Western Valley. Models have trouble pushing the cold far enough south and east in these situations. It's usually more likely to bank up against the Apps.