Winter Speculation 17/18 -December Thread

[Holston_River_Rambler]

I don't think I've ever seen anything modeled like what the CMC 12z is showing for 500mb anomalies over northern North America.  The way it evolves the blocking is incredible, in the sense that it defies belief (well it is the CMC at hour 240). If y'all get a chance and you haven't checked it out already, go to Tropical Tidbits and look at it.  Extreme blocking and anomalous heights from the Aleutians to the Davis Straits.  

[Carvers Gap]

I definitely like the looks of the 12z GEFS and GEPS.  No major changes in my thinking at this point.  We are just about where we can talk storm tracks(not specific storms).    The press from the -NAO is likely undermodeled, so still tough to get a good call at this point.   VERY preliminarily, initially at the beginning of the pattern it looks like hand-off situations will be present where a system tracks across the eastern US north of I-40 and hands-off its energy to the coast and potentially stalls.  Only NE TN and SW VA would benefit from that, mainly the mountains.  Once those hand-offs are done(they look like sometime between March 3-5), then systems really look like they are forced to the low road.  That does coincide with earlier graphics that depict the NAO beginning to slowly weaken...and I mean slowly.  But that slight rise in the NAO(while negative) is often where big storms haunt.  Other than that...looks like a week from tomorrow or a week from Saturday is when the blocking pattern is truly felt here w seasonal to BN temps...then a step down to cold.  Just about where we can say that this is not a trend, but an actual event that will take place.  I like to be within 5 days before saying such and such pattern will change.  I have seen too many head fakes to say anything is certain.  

[Carvers Gap]

As Jeff mentioned in the historical thread, we need to eventually see systems form over Alabama or even west(or east...depends on you valley location) of there and attack the block.  Sorry Jeff if that is quoting you incorrectly.  I do not see those setups yet in the modeling because it is just too far out there(meaning past d10).  Past blocking events do support that area for storm formation, but there are times when confluence is to our east.  But here is an idea....as the trough retrogrades it is likely that we will at some point fall into the slot for good storms.  Sometimes when taking a photo, a photographer will bracket a shot.  Roughly speaking if they are not sure of the exact setting, they will take a shot w multiple settings to cover their basis and one of those shots will be a winner.  I think the same thing here...as the block retrogrades at some point the sweet spot will favor us.  Now, the ten million dollar question, "When the track favors us, will there be a system in the pipeline once the 500 pattern is in our favor?"  No idea.  On the operational GFS one can see the block really "push."  The details are foggy, but the idea is that systems will be forced south before lifting north. And systems will really slow down.  Anyway, the actual events that begin the pattern shift are now depicted on the NAM.  An initial push of cold will temporarily push the SER south.  It rebounds.  That can be seen on the NAM.  After that, the globals show a very temporary SER rebound and then the retrograde begins.  

[Carvers Gap]

Lastly, I will add that we have been watching this time frame for almost three weeks beginning w the SSW discussion.  Feels like we have been watching this potential event forever.   It will be nice to see it actually happen, but man, still a week to go!  Really hoping we get 2-3 systems to track.  I am definitely prepared to go the mountains should they score.  Hopefully valley locations can get in on the act.  I think right now, all areas are still in the game.  By early next week, hopefully we get a better idea if this potential block will produce.  Then there is the question of duration....I think it lasts a minimum of two weeks.  Not sure after that....

Great work in the historical thread by several posters...lurkers be sure to check it out.  Strong work.  

[John1122]

Looking back at the March snow events, it's impressive that the balance of them happened after March 10th. 18 out of 26 were in that time frame and only 4 of them happened before March 5th. 

[John1122]

Also, we are breaking record temps set in 1980, tomorrow the record is from 1996. Both featured large March snows. 

[John1122]

The Euro is about 45-50 degrees warmer than the GFS at day 10 for the area. 20s and 30s vs upper 70s. 

[nrgjeff]

Euro ensembles is probably not cold enough at the surface. Its own 850 is colder. The 500 pattern is definitely cold. Some of its clusters catch the surface cold. Euro weeklies do bring in cold weeks 2-3, which makes sense. CFS still agrees.

Tough forecast since we are looking to the Atlantic for help for the first time in several years. Pattern recognition says -NAO is cold. However it is tough to use pattern recognition when the initial situation is so crazy: Record high 500 mb heights mid-Atlantic. Snow in southern Europe. Arctic temps 45 degrees AN. Only thing we know is SSW is not dull, lol!

First cold shots, if/when they come, will probably under achieve. Last ones may over achieve. Goal is to gin up a winter storm toward the end. If not, we'll go storm chasing!

[jaxjagman]

On 2/17/2018 at 2:02 AM, jaxjagman said:

I'm gonna take a stab at this and might be wrong.But looking at the GFS,Euro and EPS they all show this around day 10 a ridge into Korea,with a trough going into Mongolia and lower heights off the Japan coast.This should set up a potential Tn Valley ridge into the 1st week of March(5th or 6th?) that moves east and the Atlantic low being shown should be further east than what is being shown.

I still believe this is the period to watch.You have a system going into Korea that could  finally give us a brief +PNA that would rise the heights into China and Mongolia somewhat before hand but another trough is being shown right after so that PNA ridge would once again get squashed.There could be a decent system that the models arent picking up quite yet.Not saying it will happen but just something to watch

 

[Carvers Gap]

I said I wouldn't add much until we were closer to the time frame and details became clearer.  The 0z EPS/Euro combo inside of d10 look like a reasonable progression now as it steps down to cold.  One slp bowls to the EC and deepens off the coast and moves very slowly once out to sea on March 3rd.  The entire progression is slower (than what we have seen this winter) due to the block.  The ridge that forms behind the deepening slp has nowhere to go as it is forced through the East and quickly squashed.  So, there will be a brief warmup behind the first low.  Then another low deepens and pulls back the trough that is off the coast.  JB mentioned several days ago that he thought this might happen.  Still, nothing is certain right now as one only need to look at the wx models to see the multiple solution paths available.  After that is when the fun begins.  As others have mentioned, the second and third weeks of March increasingly appear to be our window.  The first system has always been unlikely for us.  What comes after is still buried in the chaos of modeling.  Most global ensembles are now in relatively good agreement about the NA 500 pattern, though the aforementioned details are not clear yet.  Things still appear to be on track for an eastern trough to be a staple over the EC beginning w a step-down pattern beginning around March 3rd which would be next weekend.  The transition will begin this week w mountains snow showers possible next Friday afternoon or night.  

 

[Carvers Gap]

The trough on the 12z Euro along w the 0z Euro now deepens the trough in the East.  Blocking up top w a PNA ridge.  The SSW, MJO, and SOI have done their work.  It goes to show that those teleconnections and indices do actually have very good merit and are not just February discussion fodder as some felt after last winter.  While there is certainly no magic bullet, he MJO has been a very good forecasting tool this winter.  Outside of the QBO, it may very wall have been the most accurate indicator at range....well that and the current ENSO state.  Compared to the low 80s of last week, highs in the upper 30s and/or 40s during coming weeks in NE TN could potentially seem foreign for sure.  (Of course that could all change...I certainly did not envision a week's worth of record highs in the cards for Feb, including the all-time record high for Feb.)  I think the mountains at least will see snow showers around Friday.  What a flip.  A few folks on this forum have been working this pattern flip for over three weeks beginning w SSW.  Excellent work.  Will be nice if it verifies.   One thing of note as someone will inevitably review these notes at a much later date, the actual blocking was pushed back 4-5 days from late Feb.  Seems I get that reminder every time a big Greenland block is shown.  The models jump the gun a bit, but usually it still verifies.  Lastly, I will add that the -QBO has been a good indicator as well.  Certainly we have seen incredible warmth during weeks 2-3 of February though week one was mostly BN.   Weak La Ninas are known for wild swings and this winter has been no different.  Wildfires in California while the EC was in the freezer during early winter..and then a total reversal.  However, one thing that has been present is high latitude blocking.  So, as we read back over these notes during coming seasons...a good hint at least some very cold weather over the Valley(evidenced by late Dec and Jan) is a crashing QBO in late Fall or early winter.  It may very well be correlated to a Greenland block but the sample size is likely not big enough to make that call yet.  Again, I ignored that index last winter even though Isotherm used it...and this winter I learned my lesson.  Hopefully, I will have time to do a post winter season writeup about what worked and what did not.  Obviously, the severe cold of late Dec/Jan and the extreme warmth of weeks 2-3 in Feb will be the big stories...however March is yet to be written and neither is what happens when this block takes hold.  We are very fortunate to have this reshuffle for without it....I think the torch likely could have continued or maybe it was just a precursor?  What has been nice is that during a true torch, this forum has not had any trolling by those frustrated with what they cannot control.  Speaks to the quality of posters on this forum.

 

[Carvers Gap]

Here is the 12z EPS 10 day temperature mean (d5-d10).  As you can see, we are not just talking about the d10+ pattern any longer.  We are almost in range of the NAM.  The switch to cold begins on Friday if the EPS is correct.  Look at my earlier post for how I think the step down pattern occurs.  Cold -> brief warm-up -> colder.  Very stormy look.  Some model runs seem locked on Miller Bs and others just slide everything through the Deep South.  That said, it seems like many of the models really like storms being pushed SE and then handing off energy to the coast.  I do think we might see a Miller A as that fits blocking climo.  So storm details are pretty inconsistent.  The image below includes a brief warm-up which washes temps out a bit.  We had temps last week that were 30F+.  During week 2, we could see temps 5-15 below normal.  That is a BIG swing.  The 500 pattern still shows a nice retrograding trough into the eastern US through d15.  Of note the block does slide over the Hudson late in the run.  As for the forum area, this will be the opposite of what we have seen for much of the winter season excluding the torch.   Temps will be colder closer to the EC(meaning the eastern Valley), but eventually the entire forum area will be cold relative to normal as the trough and block mature.  Again, absolutely no guarantees for snow....but weeks 2-3 still look very storm and cold relative to normals.  The control is stone cold w temps 8-13C BN around d10...not sure how much stock I put in the control, but it does show a more extreme look.  It is not out of the question that we could see a 40-45 degree temperature swing in regard to highs last week - if the control is remotely correct.  Remember again, the map below is in Celsius. 

[Holston_River_Rambler]

I'll add that looking at the MJO, (seeing your post Carvers prompted me to look at it for the first time in several days) I wish I had a screenshot of what the Euro kept forecasting for it around Feb 14 or so. It took a bit, but once it got out of phase 7 it has taken almost exactly the path the Euro was showing at that time.  I remember it so distinctly because I thought it just looked odd that it seemed to mirror the edge of the COD through phases 8 and 1, but never went in (at the time of that forecast anyway until it got to around phase 2-3). Now, that seems to be the path it took.

But I also remember the Euro wanted to crash it into the COD when it was in phase 4 or 5, way back in January? but the GFS said "nope, record amplitude territory for phases 6 and 7". While it never got "off the charts" like the GFS was showing, it did get to a very high amplitude. So maybe there's something to the GFS being better when initializing in phases 4-5-6, and the Euro elsewhere.   Here is a link to an article that includes some of that information.  https://journals.ametsoc.org/doi/full/10.1175/JCLI-D-13-00480.1

To add what you said about the forecast MJO as of now, if it continues to be a good tool for this winter, splitting the difference between the current Euro and GEFS wouldn't look too bad over the next 15 days!  Here's hoping it holds or even gets better! Also of note, if the diagrams (RMM composite observations vs forecasts) in that article linked above are correct, the Euro likes to try to crash the MJO into the circle of death too quickly when initialized in phase 1.  

[Carvers Gap]

9 minutes ago, Holston_River_Rambler said:

I'll add that looking at the MJO, (seeing your post Carvers prompted me to look at it for the first time in several days) I wish I had a screenshot of what the Euro kept forecasting for it around Feb 14 or so. It took a bit, but once it got out of phase 7 it has taken almost exactly the path the Euro was showing at that time.  I remember it so distinctly because I thought it just looked odd that it seemed to mirror the edge of the COD through phases 8 and 1, but never went in (at the time of that forecast anyway until it got to around phase 2-3). Now, that seems to be the path it took.

But I also remember the Euro wanted to crash it into the COD when it was in phase 4 or 5, way back in January? but the GFS said "nope, record amplitude territory for phases 6 and 7". While it never got "off the charts" like the GFS was showing, it did get to a very high amplitude. So maybe there's something to the GFS being better when initializing in phases 4-5-6, and the Euro elsewhere.   Here is a link to an article that includes some of that information.  https://journals.ametsoc.org/doi/full/10.1175/JCLI-D-13-00480.1

To add what you said about the forecast MJO as of now, if it continues to be a good tool for this winter, splitting the difference between the current Euro and GEFS wouldn't look too bad over the next 15 days!  Here's hoping it holds or even gets better! Also of note, if the diagrams (RMM composite observations vs forecasts) in that article linked above are correct, the Euro likes to try to crash the MJO into the circle of death too quickly when initialized in phase 1.  

It is interesting.  Last year it correlated quite well...problem was, when it went into phase 8 the cold air was gone from Canada.  A trough filled with Pacific air doesn't help too much if I remember correctly.  Ha!  So, while it does a decent job w the 500 pattern there has to be a cold source, and that made last winter's discussion moot.  There are notable times when it missed...maybe the winter of 84-85 was one of those during February.  JB showed that one. The GEFS has done really well this winter w the MJO.  Seems like the Euro has had a bias for the COD.  I am thinking most models missed the stall in phase 7 at first, though certainly some of them did see it before they were right on top of it so to speak.  Isotherm actually called the stall...seemed like he noticed a hiccup that would lead to a stall in phase 7.  The best model IMO, has been the BOMM from Australia.  None of them are perfect though.   The amplitude of the MJO makes a big difference as well...that crazy high amplitude that the GEFS had in phase 7 basically verified to my surprise.  And what resulted here?  A record EC heat ridge.    The JMA does really well, though I think it missed the phase 7 stall.  The GEFS and Euro both caught the stall at varying points.  But again, I am a big fan of the BOMM though.  And some winters different tools work better than others.  The EPO index was a great tool during early and mid winter.  Now, the NAO is about to take over as the main driver.   My absolute favorite teleconnection, index, tool, etc....is a trough just to the east of Hawaii.  When that is there, we generally see cold here.  I suspect the MJO is probably related to that feature as the thunderstorm complexes in the western Pacific likely have a big say in where Pacific 500 patterns are placed.

I will add...the absolute best forecasting tool is still ENSO.  Oceans cover a large portion of the planet and thus where the heat is or isn't makes a big difference.  I definitely prefer a weak ENSO state.  Too strong in either direction, and it just makes things too warm here.  I have my fingers crossed that we have a weak Nino or that we are just north of neutral for next winter.  The QBO might flip back as I think it will be stale or close to a flip by then....and that could be a slight problem.

On a sidenote, the EPS really struggled w not deepening troughs enough this winter and struggled w its usual SW energy bias.  However, to its credit, it nailed the recent EC mega ridge well before any model had it.  Inside of d7, the Euro suite is still tough to beat as long as one knows its biases.  Past d7, the GEFS has not been bad lately.  I have not seen verification scores...but I am able to use it to some degree.  It does have a bias of overdoing the NAO past d10...but I think it has done pretty well w the upcoming flip.  I am still amazed that it nailed the strat warm from 16 days out.  Pretty awesome that humans have designed a computer that can model something like that.  

[John1122]

Someone may score a miracle on the river in the next two weeks if the cold pattern verifies. It'd take a potent precip rate storm, likely happening at night to get a lot of accumulation. March storms are capable of that though. North/Eastern areas have about 3 weeks left for something to hit, 4-5 above 2500 feet. SW areas probably have 10 days or less. It usually takes a rogue ULL to get lower elevation snows in March west of Nashville. Especially in the current ultra heat climate we are seemingly locked into. Based on general climo, I'd give someone below 2500 feet a 10 percent shot at a 2+ inch snow event in the next couple of weeks. 2500-4000 probably 50 percent, above 4000 probably 75 percent, above 6000 it's a near certainty and may happen into next weekend.

[Carvers Gap]

Back to the upcoming pattern...absolutely not saying this is going to happen...but the 18z GFS around d10(240) shows where we need the trough to eventually get.  It has been a bit too far to the east for my liking on the operationals.  Still scoots too far to the east after that...but that is a good visual for where we need it in order to have confluence where it can help us.  Normally, I don't talk specifics about models at 240...but it is a good illustration of where we need things.

addendum....definitely like the 18z GFS.  Who knows if it verifies, but I can still like it, right?   And then it goes totally wonky after I say that.  Ha!

[Carvers Gap]

13 minutes ago, John1122 said:

Someone may score a miracle on the river in the next two weeks if the cold pattern verifies. It'd take a potent precip rate storm, likely happening at night to get a lot of accumulation. March storms are capable of that though. North/Eastern areas have about 3 weeks left for something to hit, 4-5 above 2500 feet. SW areas probably have 10 days or less. It usually takes a rogue ULL to get lower elevation snows in March west of Nashville. Especially in the current ultra heat climate we are seemingly locked into. Based on general climo, I'd give someone below 2500 feet a 10 percent shot at a 2+ inch snow event in the next couple of weeks. 2500-4000 probably 50 percent, above 4000 probably 75 percent, above 6000 it's a near certainty and may happen into next weekend.

Good post.  Reasonable odds.  I would probably place NE TN in the 30-35% range even in the Valleys....and just make those odds for all of March.  I think next week is probably a wash.  Weeks 2-3 look like the best weeks IMO.  If the odds are just for the next two weeks, then yes...ten percent is about right, because week one is likely a no-go.  Add in week three, and maybe I nudge them up a bit.  But for sure, after week 3 we are all headed for spring....now, watch it snow then because I said that.  You all can thank me later.  6,000' always amazes me...it snowed last year during May.  I always tell a good friend of mine that at that elevation the weather is more similar to Quebec.  The grimace, because they live well north of here.  I once took a guy from Maine to Carvers Gap in the dead of winter...he was shocked at how cold it was up there.  The snow was like 2-3' deep at the time. 

[jaxjagman]

Why can't we ever get that look in Jan?Just sweet looking

 

[Carvers Gap]

Definitely seeing an uptick in activity after this weekend's storm.  The Euro control had two massive storms.  The next piece of energy looks like it rolls through from d8-10.  Models seem to have trouble tying to decide whether they want a handoff of energy or a Miller A type look.  The EPS has two camps w a lean towards a Miller b or hybrid.  The GEFS takes the low road and scoots off the coast.  Either scenario is possible IMO.  It is the storm directly after that(admittedly way out there) that might be our shot....third storm counting this weekend's as number one.  Though I would not sleep on the second storm either as all of these storms are influenced by the one in front of it....Just looking at the EPS, it looks like at three pieces of energy move through the block.   Details will certainly change regarding these as they are spaced between d5-12.  And spacing, I do like the spacing of each system as they leave room for the next system to develop.  I think, at the least, the mountains see at least one nice event.  I will drive there if possible.  But the valleys are not out of this by any means.  Looks like we have some systems to track.  

[Carvers Gap]

Definitely an interesting run of the 12z Euro.  Looks to me like the first system misses to the north as we knew it would...never any investment in that one.  The second system goes negative tilt at 500. It is a hybrid Miller A.  A weak area of slp forms over GA and moves to Hatteras and then goes boom.  If it just strengthens a bit earlier and maybe slows down...the track is nice.  I suspect the trend is likely to be a bit south as the models feel influence of the block. If that digs just a hair more...anyway at d7-8, still plenty of changes for that one before it comes into focus but interesting.  Then, a third system is entering in central California.  Definitely interested in the EPS run in a few minutes.

[John1122]

I don't understand the Canadian solution. Appears to show a PNA ridge, blocking in Eastern Canada, and the storm still cuts to the Lakes late run.

[Carvers Gap]

Weeklies are in...they continue to advertise a window for storms through about March 18th.  Oddly, with very few drivers in place....the Weeklies are not very warm throughout.  Seasonal to cool is probably a good word.  After a few days of warm wx after March 18th, they continue to send cold into the East.  I think it was @nrgjeff that noted a few days ago that they seemed a bit warm during the past few runs(edit: maybe it was just the Euro/EPS suite proper), but looks like they have corrected to a reasonable look given the strong blocking in place.  I will update storm tracks in a moment in this post.

Update:

-Storm tracks rotate under the block.  Some are handoffs.  Some take the low road.  

-Though the NAO returns to neutral, there is still some semblance of AN heights over Greenland and repetitive shots of cold intermixed w warm episodes.  Verbatim, that looks like a cool spring though not unbearable in terms of cold.  HOWEVER, the morning Euro run was fairly cold so that can easily influence the 46 day look.

-The snow mean is not much to brag about, BUT it would not take much to make it move up.  From W VA TO NE the mean and control definitely depict a coastal storm signal.  Not sure if climo is included which would wash out numbers here or not.

Final note:  I might do one more Weeklies updated as we are really now just about to the window of March 4-18th and global models have that in sight now.  After that, spring will surely take a firm hold(not that it didn't last week) for most non-mountain areas.  We should see 4-5 systems that will give us a chance.  The ensembles and operational are all over the place as the GEFS is more progressive and slides many systems off the coast.  It sometimes overdoes the -NAO IMO as a bias...but who knows.  The EPS/Euro is not deep enough.  If one were to take the happy medium...then we have a shot.

Either way....the mountains (and maybe some areas of NE TN) really look like they have multiple opportunities. For those of us that live close by....might have to chase a storm or two if we don't score here.  Right now, still think that March 7-18 is the best window...so still just a hair outside of the Euro's wheelhouse.   Some potential, but details far from certain.  Certainly during March the odds are generally against us....always a safer bet to take nothing.  However, it does snow in March in the Valleys...especially north of I40.  I am definitely interested in the pattern for sure.  Chances are much better than last March when winter was basically off life support.  Have a good evening!

[Carvers Gap]

5 hours ago, John1122 said:

I don't understand the Canadian solution. Appears to show a PNA ridge, blocking in Eastern Canada, and the storm still cuts to the Lakes late run.

I have seen so much weird stuff this winter.  Seems like every odd solution that I laugh at comes to pass.  But yeah, odd deal.  Have to think the block really kicks in after NE low this weekend rolls through and its follower ridge....then the block really takes hold.  I would be surprised to see cutters after that.

[Carvers Gap]

E TN post....Sorry to be a thread hog tonight, but just noticed where MRX is listing rainfall totals in excess of 2" for the southern Valley and around 2" for the northern Valley....That would be a total mess up here.  Whew!

Hydrologic Outlook
National Weather Service Morristown TN
301 PM EST Mon Feb 26 2018 /201 PM CST Mon Feb 26 2018/

...Heavy Rains and Possible Flooding Wednesday into Thursday...

A slow-moving weather system will be moving into the upper
Tennessee Valley and Southern Appalchians area late Tuesday night
and lingering into Thursday. Rain will begin moving in after
midnight Tuesday night, with rain continuing into Thursday morning
before tapering off to just some lighter showers Thursday
afternoon. The rain may be heavy at times across portions of the
area, especially Wednesday into Wednesday night. Due to these
persistent rains, many streams and rivers will be rising, and
flooding could occur in some areas.

There is still quite a bit of uncertainty about where the heaviest
rains will occur as well as total rainfall amounts.  We will
continue to monitor this situation and will pass along more
information as the system approaches. There is a significant
possibility of Flood Watches being issued for at least some
parts of the area for the mid week period.

[1234snow]

0z GFS shows a large trough move east around hours 200-240. By hour 240 the trough is forced to sag south and cutoff around the TN/Ohio Valley due to the -NAO. The trough then turns negative tilt and a mountain/East TN snowstorm is underway. This seems to be the first snow solution within 240 hours from the GFS. I know it’s only one run and a long way off but maybe this is finally where pattern recognition can turn into tracking actual storms.

[jaxjagman]

4 hours ago, Carvers Gap said:

E TN post....Sorry to be a thread hog tonight, but just noticed where MRX is listing rainfall totals in excess of 2" for the southern Valley and around 2" for the northern Valley....That would be a total mess up here.  Whew!

Hydrologic Outlook
National Weather Service Morristown TN
301 PM EST Mon Feb 26 2018 /201 PM CST Mon Feb 26 2018/

...Heavy Rains and Possible Flooding Wednesday into Thursday...

A slow-moving weather system will be moving into the upper
Tennessee Valley and Southern Appalchians area late Tuesday night
and lingering into Thursday. Rain will begin moving in after
midnight Tuesday night, with rain continuing into Thursday morning
before tapering off to just some lighter showers Thursday
afternoon. The rain may be heavy at times across portions of the
area, especially Wednesday into Wednesday night. Due to these
persistent rains, many streams and rivers will be rising, and
flooding could occur in some areas.

There is still quite a bit of uncertainty about where the heaviest
rains will occur as well as total rainfall amounts.  We will
continue to monitor this situation and will pass along more
information as the system approaches. There is a significant
possibility of Flood Watches being issued for at least some
parts of the area for the mid week period.

You're ok,keep posting.Our worse case scenario would be if a boundary would happen to stall out.Luckily we get a couple days break in-between.This will be our 2nd wettest Feb on records.Crazy winter.

 

Hydrologic Outlook
TNZ005>011-023>034-056>066-075-077>080-093>095-272100-

Hydrologic Outlook
National Weather Service Nashville TN
256 PM CST Mon Feb 26 2018

...Heavy Rainfall Expected Across Much of the Mid-South From Early
Wednesday Through Thursday Afternoon...

Rainfall is expected to return to Middle Tennessee early
Wednesday, falling on saturated grounds unable to absorb much
more. Area creeks, streams, and rivers are running high and a
number of river gauge locations are above Action Stage. Rain is
expected to move out Thursday afternoon, leaving total rainfall
amounts of several inches across the area.

Runoff from this event will likely cause rises of smaller creeks
and streams, especially Wednesday evening when intense thunderstorms
may produce flash flooding. Minor flooding may also be possible
on the larger rivers into the weekend, especially on the lower
reaches of the Cumberland, Duck, and Tennessee River basins.

Model guidance indicates storm total rainfall amounts of 2 to 4
inches can be expected, with isolated higher amounts possible.
Where the rain falls varies from Southern Kentucky and most of
Tennessee, to Northern Mississippi and Northern Alabama. This lack
of consistency with where the rain will fall creates uncertainty
with total rainfall amounts, as well as the severity of flooding.

 

 

 

[Holston_River_Rambler]

Seems to me some good looks start showing up after about hour 230 on the 6z GEFS individual members (Ensemble member precipitation type) on the College of Dupage site http://weather.cod.edu/forecast/

By good I mean a variety of ways for snow to happen and even multiple systems.  Obviously no guarantees of anything, but for me it seems to look better than anything I've seen this winter.  Maybe I'm misinterpreting and maybe it'll change significantly next ensemble cycle, but if any of y'all who are better at using these tools want to comment, please do.  And looking back at the 0z GEFS, the mean snowfall actually looked better, though the individual runs didn't seem as good to me. 

 

 

[Holston_River_Rambler]

In terms of the rain, the most concerning thing for me is that the short range HiRes models seem to want to show heavy rain and maybe t-storms (sorry not so good at telling the difference on the models) setting up somewhere across on what looks like a boundary running through TN. Everybody gets heavy rain, but man, if that boundary with the heaviest rains sets up somewhere and doesn't move for a few hours, someone's going to have a really rough time. 

[nrgjeff]

Cooling trend actually starts this Friday. As usual it'll take a few cold fronts to get to BN temps. Should be there by Day 7-8. Could be choppy mid-March but I figure at least one cold week. The pros..

1. Some blocking is noted, though it is not well coordinated. 2. Some clusters are colder than ensemble means. 3. Some members have decent surface low tracks, though not many.

Cons: The usual we live in the South. Europe might have taken all the glory. Add Rome, with its scenic palm trees, to the list of cities ahead of Chattanooga snowfall.

After March 15 of course it is a race against the clock. Until then, anything can happen!

[Carvers Gap]

Feb 20th...two records

2015:  -13F

2018:  79F

92 degree range for that date during a three year period.   Pretty crazy.