Winter 2015-16

[Mr Bob]

We usually leave the fantasy progs for the banter thread in this sub forum . Pattern is def changing but the Euro EPS is not yet a great pattern for here so an outlying GFS op panel that shows a great pattern is not evidence of anything.

[Stormcatt]

We usually leave the fantasy progs for the banter thread in this sub forum . Pattern is def changing but the Euro EPS is not yet a great pattern for here so an outlying GFS op panel that shows a great pattern is not evidence of anything.

I'll remember that thanks for the info. As for the pattern no it's not great. But it's workable for many. The GEFS and EPS have a strong -EPO that builds as the runs progress . Both have the AO going negative for a period as well. I think we would all take our chances . Sure it's not perfect , but a better pattern thats serviceable is far better than the horrible pattern we have been in. I'll take my chances with a ridge-bridge any day of the week IF it verifies. It's a little weird that the eps has trended towards the GEFS as far as the EPO goes

[John1122]

The PNA ridge, which is a key key factor for wintery weather for our region, is being built on pretty much all the models. It helps everyone in the East but the Valley being further west is usually helped more than the SE. 

 

As of now, the PNA is forecast to go very positive. The AO is forecast to go negative by both the GFES and the Euro. The NAO appears split with about half it's members being positive and half negative. It averages out to near neutral. Even the EPO is forecast to tank in the long range. If the EPO does tank as forecast, I think there's a chance we have not just a cold pattern, but a major arctic outbreak might occur if all those things come together. Even above normal Canadian temps can be very cold for the lower 48.

 

Last year's cold was driven by a slightly positive PNA and a majorly negative EPO as we went into mid February. We actually had a positive NAO/AO while getting hammered by winter storms and -5 to -15 degree cold.

 

The Euro also has the MJO heading into phase 8, which is a ridge in the Rockies, trough in the East pattern that is favorable for East Coast storms.

 

Finally, I saw a Nino map, while it's very warm basin wide, it's still much colder in the Eastern sections than 1998. I want to say it's 1.2-1.6c colder on it's East side and the same amount warmer on the west side.  So even though I'd be happy with a repeat of that season due to getting up close to 30 inches of snow, I know the rest of the area not at elevation didn't do nearly as well. But it's a very different Nino and we've been in a very different pattern than it. 

[Carvers Gap]

The PNA ridge, which is a key key factor for wintery weather for our region, is being built on pretty much all the models. It helps everyone in the East but the Valley being further west is usually helped more than the SE.

As of now, the PNA is forecast to go very positive. The AO is forecast to go negative by both the GFES and the Euro. The NAO appears split with about half it's members being positive and half negative. It averages out to near neutral. Even the EPO is forecast to tank in the long range. If the EPO does tank as forecast, I think there's a chance we have not just a cold pattern, but a major arctic outbreak might occur if all those things come together. Even above normal Canadian temps can be very cold for the lower 48.

Last year's cold was driven by a slightly positive PNA and a majorly negative EPO as we went into mid February. We actually had a positive NAO/AO while getting hammered by winter storms and -5 to -15 degree cold.

The Euro also has the MJO heading into phase 8, which is a ridge in the Rockies, trough in the East pattern that is favorable for East Coast storms.

Finally, I saw a Nino map, while it's very warm basin wide, it's still much colder in the Eastern sections than 1998. I want to say it's 1.2-1.6c colder on it's East side and the same amount warmer on the west side. So even though I'd be happy with a repeat of that season due to getting up close to 30 inches of snow, I know the rest of the area not at elevation didn't do nearly as well. But it's a very different Nino and we've been in a very different pattern than it.

Good discussion. What I can't decide upon is duration. Looks like a week or two of nice, cold January temps. Then, does it keep repeating? Or does the Nino shove the trough on out? I am 50/50 right now. The CPC teleconections for today had an AO that goes strongly negative and a strong PNA that weakens slightly later in the period. But this will be jarring in its nature. Low 70s this weekend. Low 40s next weekend for highs. That is gonna hurt. I have always been wary of severe storms in winter. Seems like they often precede pattern changes. Nino climo will rule the day. But if the eastern Pacific stays cooler...that would have my attention.

[John1122]

Good discussion. What I can't decide upon is duration. Looks like a week or two of nice, cold January temps. Then, does it keep repeating? Or does the Nino shove the trough on out? I am 50/50 right now. The CPC teleconections for today had an AO that goes strongly negative and a strong PNA that weakens slightly later in the period. But this will be jarring in its nature. Low 70s this weekend. Low 40s next weekend for highs. That is gonna hurt. I have always been wary of severe storms in winter. Seems like they often precede pattern changes. Nino climo will rule the day. But if the eastern Pacific stays cooler...that would have my attention.

 

It doesn't seem like the Nino has had much effect on weather thus far this season. It's been overridden by other factors. Southern California hasn't seen a ton of storms and rainfall and the PacNW, normally dry during Nino is setting records for precipitation. It's pretty much been the Arctic and the tightly wrapped polar vortex that's been keeping the cold at bay. Maybe we will transition into more of a Nino pattern, which is actually a good thing for snowfall in the area, but who knows exactly what that will mean, as Nino's have produced wildly varying weather over the years here.

[Daniel Boone]

Last February did prove we ,especially from the Cumberland's Westward, don't have to have a -NAO to get plastered. 37 inches in just over 3 weeks here near the Cumberland gap in Virginia.

[Carvers Gap]

It doesn't seem like the Nino has had much effect on weather thus far this season. It's been overridden by other factors. Southern California hasn't seen a ton of storms and rainfall and the PacNW, normally dry during Nino is setting records for precipitation. It's pretty much been the Arctic and the tightly wrapped polar vortex that's been keeping the cold at bay. Maybe we will transition into more of a Nino pattern, which is actually a good thing for snowfall in the area, but who knows exactly what that will mean, as Nino's have produced wildly varying weather over the years here.

Precip pattern(excluding this week) has not been Nino-like. Some of the temp records we broke were Nina winters. Temps can torch in a strong Nino as evidenced in the 90s. But they are rarely dry here and in the places you mentioned. They are rarely dry here in the recrent era. Put dry wx with a torch...and that is not Nino wx. WxSouth had a great write-up about the upcoming pattern change today. FWIW, I do think the new pattern will be a truer Nino pattern. These heavy rains here and the winter in TX seem to reflect that. I think the wall-to-wall record heat is gone for quite some time. Sure, it will go zonal for periods of time...but the record heights of the past month are just about behind us. The mean trough should be over the eastern US for the first half of January at least.

[Carvers Gap]

Last February did prove we ,especially from the Cumberland's Westward, don't have to have a -NAO to get plastered. 37 inches in just over 3 weeks here near the Cumberland gap in Virginia.

Used to have a poster near Jonesville. Yep. Last winter was pretty awesome and the NAO was awful. Had about 22" in two and a half weeks here. Snow didn't go anywhere.

[jaxjagman]

Last February did prove we ,especially from the Cumberland's Westward, don't have to have a -NAO to get plastered. 37 inches in just over 3 weeks here near the Cumberland gap in Virginia.

 

Used to have a poster near Jonesville. Yep. Last winter was pretty awesome and the NAO was awful. Had about 22" in two and a half weeks here. Snow didn't go anywhere.

This is where orographic lift also is always a good thing to have, something we don't have  here.You can have flurries here that tracks yalls way,by the time it  gets to yalls way it's snow showers.But that's the life for us in the Middle and west.But last year was still weird Southern Middle Tn did rather well,i'm pretty sure they ended up with a foot give or take

[Carvers Gap]

This is where orographic lift also is always a good thing to have, something we don't have here.You can have flurries here that tracks yalls way,by the time it gets to yalls way it's snow showers.But that's the life for us in the Middle and west.But last year was still weird Southern Middle Tn did rather well,i'm pretty sure they ended up with a foot give or take

Depends on what side of the valley you live. I am in almost a rain shadow for northwest flow events and west to east events. Give me a SLP tracking to the southeast and the reverse is true. Twenty miles away in JC...the opposite of my snow advantages or disadvantages. Downsloping on big SLP's near the coast, but cleans up on northwest flow events.

[Carvers Gap]

This is where orographic lift also is always a good thing to have, something we don't have  here.You can have flurries here that tracks yalls way,by the time it  gets to yalls way it's snow showers.But that's the life for us in the Middle and west.But last year was still weird Southern Middle Tn did rather well,i'm pretty sure they ended up with a foot give or take

We also get the following scenario from time to time...heavy snow right up to the border on the NC side and nothing here. This winter could be one of those winters. Maddening. Good thing is we can chase those.

[jaxjagman]

Depends on what side of the valley you live. I am in almost a rain shadow for northwest flow events and west to east events. Give me a SLP tracking to the southeast and the reverse is true. Twenty miles away in JC...the opposite of my snow advantages or disadvantages. Downsloping on big SLP's near the coast, but cleans up on northwest flow events.

Yeah you are further off.I get annoyed though watching at times, watching the weather radar and seeing a dimple around my house then it explodes as it gets to Cookeville.

[John1122]

While we can do well without the NAO cooperating. If it goes negative during an El Nino, look out. Especially during moderate and strong El Nino's. Nashville's snowfall total goes up by 300 percent with a -NAO/Strong Nino vs without for instance. La Nina was bad to us last time through too, but Nashville is also generally above normal in snowfall during La Nina years. 

 

We in the entire valley, don't often get to experience the huge snows of 15+ inches, at least those of us below say, 4000 feet. Those huge storms are more common closer to the coast. We can get persistence snows here and it will add up 1-3 inches at a time to get me over 20 inches on the season fairly often. But 13 inches is the biggest snow total from a single storm I've had here since 1998. Last year would have probably cracked that but for the massive sleet totals.

 

I'd be curious to see the top 20 snowfalls from Crossville and Tri-Cities of all time. I don't think all of Nashville's top 10 are greater than 10 inches. I know all of Memphis' aren't. Seems like Knoxville had a 9,9 in their top 10. 

 

You move east of here and North Carolina will see far less days with flakes in the air outside the mountains, but they have far greater potential for 15+ inch mega storms.

[Carvers Gap]

KTRI's data is a mess as we have discussed. Some really big snows have fallen here. 15+ is uncommon but not rare...I think. But again, climo is a mess here.

[jaxjagman]

While we can do well without the NAO cooperating. If it goes negative during an El Nino, look out. Especially during moderate and strong El Nino's. Nashville's snowfall total goes up by 300 percent with a -NAO/Strong Nino vs without for instance. La Nina was bad to us last time through too, but Nashville is also generally above normal in snowfall during La Nina years. 

 

We in the entire valley, don't often get to experience the huge snows of 15+ inches, at least those of us below say, 4000 feet. Those huge storms are more common closer to the coast. We can get persistence snows here and it will add up 1-3 inches at a time to get me over 20 inches on the season fairly often. But 13 inches is the biggest snow total from a single storm I've had here since 1998. Last year would have probably cracked that but for the massive sleet totals.

 

I'd be curious to see the top 20 snowfalls from Crossville and Tri-Cities of all time. I don't think all of Nashville's top 10 are greater than 10 inches. I know all of Memphis' aren't. Seems like Knoxville had a 9,9 in their top 10. 

 

You move east of here and North Carolina will see far less days with flakes in the air outside the mountains, but they have far greater potential for 15+ inch mega storms.

Most snowfall, 24 hours: 17.0", March 17, 1892

Most snowfall, Christmas Day: 2.7", 1969

Most snowfall, 1 month: 21.5", March, 1892

Most snowfall, 1 season: 38.5", 1959-60

Least snowfall, 1 season: Trace, (1949-50 & 1907-08)

Earliest measureable snowfall: 1.0 inch, October 30, 1925

Earliest snowfall, 4" or more: 7.2", November 2, 1966

Latest measureable snowfall: 1.5", April 25, 1910

Latest snowfall, 4" or more: 4.5", March 24, 1940

 

58-59 season was a weak ElNino,this is snow records for Nashville

 

Edit this:scratch the 58-59 talk.Most snow for a season was in 59-60 is was a neutral

[Coach B]

But last year was still weird Southern Middle Tn did rather well,i'm pretty sure they ended up with a foot give or take

I'm 50 miles south of Nashville and ended up with only 4.9" on the season last year. Admittedly it was one of the worst since I've lived here in relation to Nashville. We were missed to the se a couple of times and the Nashville area did much better on the late season storm due to mixing issues here. I have lived in middle TN all of my 41 years and OHX has often seemed to struggle in relation to the rest of middle TN. I don't know if its because of the relatively low elevation, heat island issues, bad luck, or measuring differences. I've lived in my present location well south of Nashville for the last 15 years and have done better most of the years since I've been here. The only thing I can come up with other than heat island is some elevation. A good bit of southern middle TN is close to or over 1000 feet while much of the Nashville metro is closer to 400 to 500 range.

[Daniel Boone]

Knoxville has actually officially recorded over 22 inches in one storm. Forget what date. You can find it online. Here in Lee county Virginia it varies greatly due to part of county being in upper tn. Valley while northern section is on a plateau. Jonesville reported 19" from the Feb. 21 storm last February. 24" was on the ground in the level at its deepest there,while Keokee in northern Lee reported 36"!

[John1122]

If the NAO truly goes negative in the next week or so, look for good times for some of us during that time frame or shortly after. -NAO with a Nino is a strong signal for above average snowfall for our entire region. +NAO with a Nino is a strong signal for way above average snowfall for the Texas panhandle and we see what has happened to them.

[Carvers Gap]

Where we have been... 

A record warm or top-five December is on tap for most in the TN Valley.  That is a torch by anyone's standards.  KTRI is at an incredible +10.9 and that is without today's mid-70s for highs included.  The month had been relatively dry(until recently) for NE TN and excessively warm.  This sparked some conversation regarding the La Nina "characteristics" derived from the coupling of record warmth and dry conditions.  At KTRI, many of the records that were difficult to break were from 1984, a warm month which flipped to record cold the following January. 

 

Facebook post by MRX today...

 

KTRI departures (notice the +20 days)

 

 

Where we are...

Though the temps continue to be very warm, the precip pattern transitioned to a very wet pattern over Christmas.  Now, the map of NA does resemble a typical Nino map with warmer temps against the norm over the northern latitudes.  But let's face it, very few saw +10.9 at KTRI.  I thought we might be a top five month, but not of that magnitude.  The Nino appears to be slowly dipping.  Remember, many were expecting a rapid drop.  Not sure if the graph below would be termed "rapid."  But, it is dropping.

 

Recent rainfall...

 

Snapshot of today's temps in the eastern Valley...

 

Nino

 

Where we are headed...

Today's temps at KTRI at least made it to 74.  New Year's Day will have a high of 40.  Flip, pattern change that is not a flip, or relaxation?  Currently, I lean towards a moderate flip of the pattern.  IMO the mean trough will be over the eastern US for the rest of the winter which includes January and February.  The ridge in the west.  Cooler temps in the SE vs the norms compared to the northern latitudes.  The potential is there for at least an Arctic outbreak or two based on the CPC ensembles for the AO.  It is going to crash.  How far does it crash is the question?  The PNA is forecast to remain positive throughout its CPC ensemble run today.  The NAO...now, there is the fly in the ointment.  Will it go negative?  I am 50/50 on this.  Today's CPC ensembles show it taking a look at negative.  However, negative winter NAOs have been like a purple unicorn lately...non-existent.  I don't think anyone knows the answer to whether it goes negative.  Some runs on the GFS have shown rising heights over Greenland only to erase the "thought" on the next run.  So, looks like a PNA ridge with cold diving into a trough centered a little further east than last winter.  What does this all mean?  Well, this crazy east coast ridge is gone for a while...hopefully for most of the rest of the winter.  Going to get some zonal.  Going to get some seasonal cold which in January is enough for wintery precip if we don't dry out.  Maybe we get some Arctic cold, but that is tougher as the southern jet to our south will want to kick-out any deep trough that might allow a cold air mass to plunge into it.  If we get a good east coast storm, that might do the trick.  It almost seems like the set-up we need is a "storm to set the stage for the next storm."  First storm pulls down cold air.  Second storm heads into the cold air a few days later.  Bottom line, I will take average temps in January with a strong Nino and roll the dice.  The models will be all over the place right now as the pattern shifts.  But I like normal temps for the rest of the winter with a chance at below normal temps if recent model trends verify.  I also like the idea of several chances at winter weather.  No way I am calling for above normal snow - would be a jinx.  But I think we will have events to follow.  Looks like the potential for a fun January and February if you like to track storms and/or cold in the SE.  But still a few pieces of the puzzle needed before I will make that last statement definitive.  But hey, where we are headed is 10x better than where we have been in terms of winter.

 

AO

 

PNA

 

NAO

[John1122]

Excellent post Carvers.

 

The AO going negative will often, but not always induce a negative NAO.

 

This is the look for a typical -AO.

 

 

 

This is the typical pattern with a +PNA

 

 

This is the pattern with a negative EPO.

 

 

 

The PNA is forecast to go positive, the AO is forecast to go very negative, the EPO, which is currently around +250 is forecast to head to around -200 in about 10 days. If all these line up, we should see some very cold weather over the Eastern US. If the NAO actually manages negative we would be in the perfect winter solution.

 

You mentioned December 1984 and it's excessive warmth. The sea surface temps around the Eastern U.S. were also very similar in December 1984. 

 

In late December 1984 the EPO was weakly positive. It turned to -144 by January 10th. The PNA was very negative throughout December 1984. It turned very positive during early January 1985 then it was moderately positive through the huge cold snap. The AO was mostly positive throughout December 1984. It turned negative in Early January and of course deeply negative by mid January 1985. The NAO was neutral in early December 1984, moderately positive Christmas week, then it went moderately negative in early January, then mildly negative to neutral leading up to the Arctic invasion, then it was moderately negative through the huge outbreak. 

 

Last year we never got cooperation from the AO and NAO. A deeply negative EPO and a  mildly positive PNA did the work of getting us cold and of course snowy/icy by February.

 

If we can get the blocking in the places the models are suggesting, we can have a very good shot at wintry weather. Possibly even very very cold wintry weather. It's just a matter of actually getting the teleconnections in place and not just having a model suggest they are going to get there eventually.

[Carvers Gap]

Great post John...You know I am still amazed we got a trace of snow here. It was record heat followed by snow followed by more record heat. During the warmest temps on record (Dec) for KTRI, we still had some snow. Stayed in the shadows for two days here. I pulled this from the forecast office in southwest TX after seeing snow at the Sun Bowl of all places. Would support your earlier comments.

[1234snow]

KTRI ended up with a record high of 77 breaking the previous record of 73 in 2008. As far as I can tell this was 1 degree shy of breaking an all time December high. That record is 78 on December 7th, 1951.

I noticed a lot of the records were from the years 1982 and 1984

[1234snow]

Also the KTRI record high for tomorrow is 69 which is within reach.

[Carvers Gap]

Sutherland had a great write-up today about the pattern transition. I will link it below. I have noticed some folks in other forums mentioning the possibility of a head fake and a return to warmth. I am in the opposite camp. The AO is forecast by CPC teleconnections to go strongly negative and stay there. The PNA is positive. The NAO is neutral. However, a few models hint at the elusive negative NAO. Model hugging will make you miserable during a pattern change. IMO it is just a matter of time before the atmosphere/models responds to the tanking AO.

http://www.americanwx.com/bb/index.php/topic/47332-winter-2015-2016-medium-term-discussion/page-4?

[tnweathernut]

Sutherland had a great write-up today about the pattern transition. I will link it below. I have noticed some folks in other forums mentioning the possibility of a head fake and a return to warmth. I am in the opposite camp. The AO is forecast by CPC teleconnections to go strongly negative and stay there. The PNA is positive. The NAO is neutral. However, a few models hint at the elusive negative NAO. Model hugging will make you miserable during a pattern change. IMO it is just a matter of time before the atmosphere/models responds to the tanking AO.

http://www.americanwx.com/bb/index.php/topic/47332-winter-2015-2016-medium-term-discussion/page-4?

Good post and I agree.  I'd like to get the modeled look at 360 on the EPS inside of 120 hours before getting too excited, but it appears to be the direction we are heading as the same general look is on most ensemble packages at this point.  Loving the look of the tanking AO and the ridging on the west coast (thank you again, PDO)  Generally, there's a very blocky look over the top so it's not so hard to imagine a MUCH better pattern for those that love tracking snow and ice in the southeast. (especially in light of the tremendous warmth we have seen this month).

 

That said, I really don't like the looks for anything in the first 10 days of January, but maybe just after that date we can reel something in as the pattern continues to progress. (1/10-1/15thish?) If the pattern from the 360 EPS materializes as shown (yes I know a long way out, but the direction does appear reasonable) we should have multiple events to track.

 

Really, after the extreme warmth for December I think that's about all one could ask for at this point.  As always, time will tell.

[Carvers Gap]

Good post and I agree. I'd like to get the modeled look at 360 on the EPS inside of 120 hours before getting too excited, but it appears to be the direction we are heading as the same general look is on most ensemble packages at this point. Loving the look of the tanking AO and the ridging on the west coast (thank you again, PDO) Generally, there's a very blocky look over the top so it's not so hard to imagine a MUCH better pattern for those that love tracking snow and ice in the southeast. (especially in light of the tremendous warmth we have seen this month).

That said, I really don't like the looks for anything in the first 10 days of January, but maybe just after that date we can reel something in as the pattern continues to progress. (1/10-1/15thish?) If the pattern from the 360 EPS materializes as shown (yes I know a long way out, but the direction does appear reasonable) we should have multiple events to track.

Really, after the extreme warmth for December I think that's about all one could ask for at this point. As always, time will tell.

Great post. I am intrigued by how the models moved up the pattern change by a couple of weeks. Seems a little ahead of schedule, and they are playing catch-up. Seems that big storm in the Pacific did shake-up the pattern. I like don's idea of a transitional period... 10th-ish looks about right to me if not before.

[John1122]

The GFS has beautiful teleconnections but doesn't actually present the weather in the way it would be with all those indicies in place. If the AO tanks, there's a PNA ridge, a positive PNA, a negative NAO, and a Negative EPO, we should be prepared for a stretch of epic winter weather. It can be amazingly wintery with just a negative NAO/AO or a positive PNA/neg EPO. 

[tnweathernut]

I was looking at some old maps from January of 1988 and came across some similarities in where most ensemble modeling now shows the pattern heading and the pattern in North American and Canada in early January of 1988.

I was fascinated in this storm as a kid because it brought such a large swath of snow in an almost due west to east fashion. As a kid, you didn't care HOW it snowed, only THAT it snowed!  

 

After taking a closer look I think I am even more amazed it occurred without a big low or bombing low.  It was simply a shortwave that turned the winds from the WSW, creating a long duration overrunning situation.  In fact, precipitation broke out 24 hours ahead of forecast for Tennesseans. (and others I am sure) 

 

In taking a look at the EPS graphic from DT, I compared it to the upper air pattern from that storm in early January of 1988. The similarities are quite remarkable IMO.

 

 

and the 500mb map from 7 am on January 6th and the snowfall map too (from the 2012 American Weather case study - by Robert, I believe)

 

 

The full case study can be seen here.

http://www.americanwx.com/models/raleighwx/studies/Jan1988.html

 

I am certainly not saying another great overrunning storm will occur.  We have to reel the modeled pattern in before looking at more specific threats.  All I wanted to do was point out the similarities noticed.  Time will tell, and history will note (good or bad) which direction we go and where the snow eventually falls.  

[tnweathernut]

Here is the northern hemisphere 500mb anomaly from the 6th-8th in 1988.

 

[John1122]

Natural gas has been spiking the last two days, reports from weather services dealing in the energy sector are saying that we will be heading into a deep freeze in mid January and beyond. The forecast is for cold to come, a brief warm up, then sustained cold from Mid January on for the East. The article I read said the South to the Southeast would be the coldest as compared to normal. When the people with money riding on getting the weather right start honking the cold signal, it gives me even more hope that the pattern is truly changing.