2016-2017 Great Tennessee Valley Winter Discussion

[BlunderStorm]

Just now, John1122 said:

00z Euro has a hurricane basically sitting off the coast of South Carolina D 10. 

Still fantasy land I suppose but that is nearing a somewhat reasonable time frame for speculation a day or two later. Eh probably just a blip if I am not mistaken?

[tnweathernut]

What I find fascinating when looking at the 0z Euro is the painting of a pattern that is supportive of having a cutoff somewhere over the southeast or Deep South.  

There doesn't appear to be real cold anywhere, but the pattern reminds me of something you'd see later in winter (March-May).  I can't remember a pattern showing like this in late January. If a cutoff does develop somewhere in the southeast, you can almost bank on there being a hefty wet snowfall just to the northwest of the slow moving track.  

Another reminder, cutoffs are notoriously hard, almost impossible to predict. Exact location and temps would likely be missed, even as close as 24 hours out. Just happy to have something to watch, what with all the warmth coming over the next week or so.

Jax, I hope you son does well in Chicago....best of luck to him!

[Carvers Gap]

<I won't rehash the upcoming pattern change, but I did find this nugget in the MA forum.  Went to CPC and copied and pasted....entire text not included.>

Prognostic Discussion for Experimental Week 3-4 Outlook 
NWS Climate Prediction Center College Park MD 
300PM EST Fri Jan 13 2017 

Week 3-4 Forecast Discussion Valid Sat Jan 28 2017-Fri Feb 10 2017 

Dynamical model ensemble guidance supports a substantial pattern change from Week-2 into the Week 3-4 outlook period. During Week-2 anomalous 500-hPa ridging is favored over Hudson Bay, with anomalous troughing stretching from Alaska down the Pacific coast, with an eastward extension along the border with Mexico. Beginning around 25 January ensemble guidance suggests ridging will begin to build southwestward across the Pacific Northwest, with troughing building in the east. The JMA is an outlier, with broad ridging forecast across North America. Some hesitation is needed with this forecast solution, as dynamical guidance has shown a tendency to abruptly adjust the general circulation pattern too quickly during the Week 3-4 period. Nevertheless, the consistent solution between the CFS and ECENS does make this solution the basis for the present outlook; however, probabilities are damped based on recent performance in pattern change scenarios.

 

[Carvers Gap]

12z EPS finally rolling.  Great looking run.  Pattern switch still moving forward in time.  850s drop BN @ d10.

[jaxjagman]

6 hours ago, tnweathernut said:

What I find fascinating when looking at the 0z Euro is the painting of a pattern that is supportive of having a cutoff somewhere over the southeast or Deep South.  

There doesn't appear to be real cold anywhere, but the pattern reminds me of something you'd see later in winter (March-May).  I can't remember a pattern showing like this in late January. If a cutoff does develop somewhere in the southeast, you can almost bank on there being a hefty wet snowfall just to the northwest of the slow moving track.  

Another reminder, cutoffs are notoriously hard, almost impossible to predict. Exact location and temps would likely be missed, even as close as 24 hours out. Just happy to have something to watch, what with all the warmth coming over the next week or so.

Jax, I hope you son does well in Chicago....best of luck to him!

Thx,he finished 23 overall.It's all good,hes learning new techs with higher starting values this year,he should get better as time goes.We go to Houston next weekend then a break (Thank God !!) for a couple weeks anyways.We should see a+PNA towards the end of the month.That ridge IN the eastern Pac should pump up the heights into the BS and AK.Prob should use the ensembles at this range but if the euro is anywhere right,it should be a decent ridge with those heights rising in Mongolia before the end of the month or around that frame

 

[Carvers Gap]

Pcbjr posted this in the SE thread...that is a pretty juicy look w at least one model wanting to hold in phases 8,1,& 2. 

[1234snow]

Pcbjr posted this in the SE thread...that is a pretty juicy look w at least one model wanting to hold in phases 8,1,& 2. 

Hopefully we can get the MJO to hold in the 8,2,1 phases instead of making a quick visit and moving on to 3 and 4. There is going to be a big storm somewhere across the east in the 9/10 day period. It may be warm but it is what may kick start a good pattern.

[jaxjagman]

1 minute ago, 1234snow said:

 

Hopefully we can get the MJO to hold in the 8,2,1 phases instead of making a quick visit and moving on to 3 and 4. There is going to be a big storm somewhere across the east in the 9/10 day period. It may be warm but it is what may kick start a good pattern.

 

Actually 2 and 3 isnt bad,though 3 in feb is better for  the Mid and western Valley,though cold air should still be in the east.GEFS shows no systems coming out of east Asia in 10 days and beyond,this is signs of cold and dry

Now if you want to believe the GFS,you have an Omega into AK,fun times for you guys in the east maybe

 

 

[Carvers Gap]

Weeklies have normal precip over most of the forum area through 46 days...6.5-8" qpf depicted.   I doubt we are dry this spring.  Could it happen?  Sure.  Always that risk.  +PNAs tend to be northern stream dominant which can lead to less precip.  But seems that the pattern in the Pacific really wants to undercut the PNA ridge w split flow.  Other than the crazy amounts on the table for the West coast, the TN Valley forum area has the best chance at decent precip in the lower 48.  I think it is a combination of the GOM being open for business, a dying La Niña, and some Nino characteristics showing in the pattern such as the Pineapple Express.  So, there is some model support for a pretty wet pattern.  With some of the fire scarred areas in the Smokies, might even be problems w mudslides and flooding.

[John1122]

Not a big fan of the GFS/GEFS trends in the last 24-48 hours to be honest.  Seems the cool down is stuck at day 13-16 every day they run and it's not really getting closer.  We don't go below normal before hour 384 on the 00z GEFS now, it has a good 500mb pattern then but it's just not being reeled in on the model. It was showing the BN temps arriving on the 25th a couple of days ago, now it's the 31st. 

The 00z  GFS OP was a bit colder a bit sooner due to a brief +pna but looks poor at 500 now by 384. EPO ridging has now turned into Aleutian ridging that run which lowers heights over Alaska and the Pacific and it's pushing the troughy look into the West coast at the end of the run. It pushes ridging into the Rockies and across the Canadian prairies which still has a trough in the East but it's likely going to be shoved off shore quickly with no blocking in the Atlantic to speak of by then.

The Canadian ens bring the cooler weather on day 13 still as well, but by day 16 the trough is heading off the east coast and above normal temps are spreading our way.  They are slowly reeling in the colder look the last few days rather than pushing it back, but it also looks very transient on that model.

[John1122]

This snapshot from several years ago is an example of what you don't want to see if you want winter here.

 

This is 384 on OOz GFS with all these features progressing eastward. Kinda heading towards the exact opposite of what we'd want to see, similar to the picture above. The fortunate thing is that it's 384 on the GFS and isn't likely to be correct, even at 500.

[Carvers Gap]

Morning update.  Here are the 0z EPS, 6z GEFS, and 0z GEM ensemble runs.  All of those models reverse the current pattern.  The timing is different for each.  The EPS has shown a consistent look for many days as has the GEM ensemble.  The GEFS, as John as noted, has moved off its spot some.  But it still flips the current pattern.  For purposes of continuity, I will begin each at 36h and put up the hour when the flip occurs and is easily recognizable.  In some cases, the look gets much more pronounced.  Note, in most cases the transition to this pattern is now seen on the operational models as they undercut the eastern NA ridge.  The beginning of the end is the undercutting of the ridge.  Now, back to the models from this morning.  Look at heights in AK before and after.   Look at the heights in the SE before and after.   I am unable to find a second reversal back to their original states in either region on the ensembles.  More notes...the MJO strongly supports more winter. The QBO on the other hand supports a return to warmer w/ its positive values.  As noted, the QBO has a small data set but cannot be discounted IMO.   With all of that said, the potential pattern change is still over a week from now.  The models are going to be all over the place as they usually are with pattern changes.  Patterns can be delayed.  Models can lose the pattern and regain it.  Sometimes, the models just flip to the opposite idea and never return.  Plenty of volatility in the coming days.  Things that I am encouraged about is that the pattern is due to flip.  Second, the potential transition to the new pattern makes sense w/ AN heights in eastern Canada retrograding into AK and the current ridge being undercut and replaced by a trough.  A stable PNA ridge is a result and is shown on all current ensembles during some time frame between d10 and d14.  And lastly, it is the weather...it does what it wants to and not what a model outputs.

0z EPS 36h

 

0z EPS 300h

 

0z GEM Ensemble 36

 

0z GEM Ensemble 276h

 

0z GEFS 36h

 

6z GEFS 300h

[JayCee]

9 hours ago, Carvers Gap said:

Weeklies have normal precip over most of the forum area through 46 days...6.5-8" qpf depicted.   I doubt we are dry this spring.  Could it happen?  Sure.  Always that risk.  +PNAs tend to be northern stream dominant which can lead to less precip.  But seems that the pattern in the Pacific really wants to undercut the PNA ridge w split flow.  Other than the crazy amounts on the table for the West coast, the TN Valley forum area has the best chance at decent precip in the lower 48.  I think it is a combination of the GOM being open for business, a dying La Niña, and some Nino characteristics showing in the pattern such as the Pineapple Express.  So, there is some model support for a pretty wet pattern.  With some of the fire scarred areas in the Smokies, might even be problems w mudslides and flooding.

After the intense drought of 2007, the pattern became wetter and by 2009 we almost had a year without a summer.  That year sunshine was at a premium and we had days and days of mild weather and soaking rains.  During mid-summer we had rounds of severe thunderstorms that seemed to occur every few days.  Could we be heading into a similar pattern?  I wouldn't complain.  Beats the boring endless sun & heat of 2016. 

[Carvers Gap]

Great discussion, everyone...point and counterpoints alike.  I have stated this before and it is one of my favorite examples...In the IDF when everyone agrees someone it is actually required to take the opposing view to prevent group think.  Iron sharpens iron. 

[JayCee]

Good morning update, Carvers.  We may not have a winter with prolonged cold in a volatile and changeable pattern like this, but like we just saw, it only takes one good cold shot to get some winter weather.  I think we, at least, have a few more of those coming up in February and possibly into March.   

[whamby]

12 minutes ago, JayCee said:

Good morning update, Carvers.  We may not have a winter with prolonged cold in a volatile and changeable pattern like this, but like we just saw, it only takes one good cold shot to get some winter weather.  I think we, at least, have a few more of those coming up in February and possibly into March.   

ha, is 2 solid weeks of 10-20 degrees AB really considered a 'volatile and changeable pattern'? Seems pretty non volatile to me, just on the warm side of the equation.

[John1122]

The 06z GFS looked better than the 00z. Huge cental Pac ridge was more muted and it made things look better down stream.  Also complete flip in the AO/NAO region. It basically went from what you don't want to see to what you do in one run. Just shows the volatility of the models long range. Especially the OP. 

 

 

[Carvers Gap]

2 hours ago, whamby said:

ha, is 2 solid weeks of 10-20 degrees AB really considered a 'volatile and changeable pattern'? Seems pretty non volatile to me, just on the warm side of the equation.

Short sleeve wx.  Nice one.  DT has a decent post on FB this afternoon.  I would post it, but am low on memory for this account.  Maybe Jax can comment more on this...but DT is concerned about severe wx in the MS, TN, and OH river valleys.  This may be a rough flip.  I hope not.  

[Carvers Gap]

4 hours ago, JayCee said:

After the intense drought of 2007, the pattern became wetter and by 2009 we almost had a year without a summer.  That year sunshine was at a premium and we had days and days of mild weather and soaking rains.  During mid-summer we had rounds of severe thunderstorms that seemed to occur every few days.  Could we be heading into a similar pattern?  I wouldn't complain.  Beats the boring endless sun & heat of 2016. 

Just a normal summer is fine w me.  The never ending warmth from last summer was a bit much.  It wasn't so much that it was extreme but the duration.  And yeah, I remember a couple of cool summers since 2000.  With a potential weak Nino developing, a slightly cooler than normal summer is an option.  Would feel much cooler compared to last summer.  I just don't want to see that extreme drought during fire season again.

[JayCee]

51 minutes ago, Carvers Gap said:

Just a normal summer is fine w me.  The never ending warmth from last summer was a bit much.  It wasn't so much that it was extreme but the duration.  And yeah, I remember a couple of cool summers since 2000.  With a potential weak Nino developing, a slightly cooler than normal summer is an option.  Would feel much cooler compared to last summer.  I just don't want to see that extreme drought during fire season again.

2009 & 2013 I believe were both very active and cool summers.  Of course, the winters associated with those years were nothing bad for cold & snow lovers either. The winter of 2013-14 was memorable and the year of the now infamous "polar vortex" invasion.  The southeast ridge was almost non-existent both of those years.  Fronts and storm systems made regular visits through the region. 

As far as those summers are concerned, local gardeners didn't have a lot of luck with the lack of extended hours of sunshine, but trees loved it.  I planted two sugar maples that year, and they haven't grown as much as that year since.  Nevertheless, my parent's garden in Kentucky produced very little in the summer of 2013 because there were literally days of clouds and rain.  The tomato plants rotted in the ground and the beans had some sort of fungal problem.  I guess it was just too much of a good thing (rain). 

[John1122]

Models wars, GEFS/GFS do not look good, GEFS goes full November/December and reloads the cold west warm east look. The GFS is all over the road run to run.

 

EPS/GEPS do look good, -EPO/+PNA look.

 

 Hope the foreigners are correct. 

[Carvers Gap]

Just reviewing earlier posts that I had made...looks like the pattern tried to flip early in December and many(including me) were fooled.  The GFS op falsely led the way followed by the GEFS and EPS...GEPS never really got on board w that erroneous flip.  All of that said.  It is currently the EPS/GEPS vs GEFS.  The American model is at odds w itself as pointed out by JB and members of other forums.  It is not in sync w its own MJO phase and SOI.  It is also not in sync w the potential warming in the stratosphere.  I think it was PSU that stated in the MA forum that it is trying to revert to the Nov pattern w different drivers of the atmosphere in place.  The GEFS is even at odds w its own operational at times.  I hesitate to call it an outlier since it is an ensemble.  It should be considered as a possible solution.  The consistency of the EPS and GEPS along w the MJO should add credibility to their solutions.  The GEFS doubled down at 18z on the complete opposite solution of the other two major ensembles. It would be a coup if it verified considering the Euro scores very well.  Time will tell.  Still 10+ days until a potential flip.  But at some point one side will have to cave.  They are just too opposite.  

[John1122]

GEFS moved towards the Euro/GGEM ens at 00z. Looks to have lower heights invading the east towards 300 and cooler air follows. Much better than the runs from yesterday.

[Carvers Gap]

Models are in much better agreement this morning.  There is a PNA ridge in the West and downstream trough in the East within a few days just after the 25th.   The 0z Euro almost has the flip on the op now at d9-10 w that last trough beginning to pop the ridge in its wake.  Other than that, nothing major that is new.  Things to watch for...does the PNA ridge broaden too much as it matures and how much cold will eventually be available?

[Carvers Gap]

Good synopsis by DT...

 

[Icy Hot]

Thanks for that synopsis. Very informative. Isn't it funny that we watch weather so closely and we have absolutely no control over it? Who would have thought it would be 69 degrees in East TN today, Jan. 16!!!

[tnweathernut]

29 minutes ago, Icy Hot said:

Thanks for that synopsis. Very informative. Isn't it funny that we watch weather so closely and we have absolutely no control over it? Who would have thought it would be 69 degrees in East TN today, Jan. 16!!!

No doubt Icy, it's a great day today!  Looking to be a great week to be outdoors, when it isn't raining.  I hope everyone gets out and enjoys it.  Looks like we find old man winter toward the end of the month and into February.  Pretty good signals on the ensembles.  

[Met1985]

9 minutes ago, tnweathernut said:

No doubt Icy, it's a great day today!  Looking to be a great week to be outdoors, when it isn't raining.  I hope everyone gets out and enjoys it.  Looks like we find old man winter toward the end of the month and into February.  Pretty good signals on the ensembles.  

Anybody have the eps?

[Carvers Gap]

5 minutes ago, Met1985 said:

Anybody have the eps?

Out to d12.5 ...looks good.  Looks like the last several runs.  

[Met1985]

1 minute ago, Carvers Gap said:

Out to d12.5 ...looks good.  Looks like the last several runs.  

Thanks Carver. To me it speaks volumes that the weeklies and EPS have been so consistent.