Winter Speculation 17/18 -December Thread

[weathertree4u]

7 minutes ago, Carvers Gap said:

I like the system at day 8.  Have for a few days.  Why?  Mainly a storm should be there....it is the end of a pattern, but more importantly, the WAR(or what becomes the western Atlantic ridge) “should” force the storm to the NE.  Literally, on the 0z GFS and Euro, the storm runs into the base of the retreating eastern NA ridge and is basically forced due north.  The ridge in front forces it north, but allows it to dig in combination with the ridge that will follow it.  That second ridge is likely to be the ridge that evolves to form our thaw.   Not sure what the trends are on retreating highs...but how quickly that high slides north eastward will decide IMO where that storm turns.  IMO, this is a bowling ball low.  So, it is questionable how much interaction it has w the northern stream...but as of 0z the point of confluence is decent for someone in our area depending on which side of the Apps this takes.  Again, I suspect it trends SE as the ridge speeds up in front of it and due to the first system being pushed SE.  And there is another point of question...the GFS sends the first vort OTS and it is gone.  The Euro sends it into the GOM where it stews. (toggle to 500vort on TT) The previous run had it on the EC of Florida.  Now, I don’t believe the Euro...but if true, that is significant.  Go back and look at what just happened w the EC blizzard.  Similar setup but further West.   SLP stalls over FL and the next system catches it, etc. DT used to always say be careful of wx models that try to repeat the setup of a big storm w subsequent energy.  That rarely happens and is often a model bias to repeat a storm. I think that is true here.  Some of those ideas come from JB...many are my own.  He has had a hot hand this winter and has had much less hype...like the old days.  But wanted to put credit where credit is due.  He called this storm several days ago.  Obviously, he is pulling for it to be more on the EC...Anyway, still a long way to go, but there is a window now for a storm.  Also keep in mind that storms can be lost during the upcoming time frame and then found during later runs.  Best guess is that we have roughly 14 more runs of the Euro and 28 of the GFS before any potential impacts. So, a lot can and will change.  The details are far from certain(options including cutters, sliders, coastals, inland runners, or nothing)....I want to see if the models continue to show this storm for the next couple of days.  In other words, need to get the storm inside of day five where the Euro has it in its wheelhouse.  Sorry...post was too long.  

Thanks for the post, I have to do allot less digging into the models now that you put it all down! Thank you!

[Carvers Gap]

As for the Sunday night system...suppression is the trend at the moment.  Off the top of my head, qpf is much lower for northern areas on the Euro compared to runs from several days ago.  Will depend on the warm nose.  The NAM still has issues w being over amped IMO.  But it did well w the blizzard so there is that.  IMO, given the setup, the arrival of precip could be faster than what is modeled.  But the air in front, like John stated, is very dry.  So, that could become virga.  That is likely why MRX was bullish though...early arrival of precip around rush hour.  Tough call.  Timing is everything with that.  Wherever that precip hits overnight could be a problem.  Have not looked at temp profiles...but one would think less precip means less energy transport from the south.  Thus, temps would be lower.  That said, sometimes heavier precip can force the air column to cool.  Will be interesting.  Those areas could be snow to ice to rain in a matter of hours.  Rain will fall as the system reaches its peak for most areas...what leads up to that will be a headache for professional forecasters.

[Carvers Gap]

6 minutes ago, weathertree4u said:

Thanks for the post, I have to do allot less digging into the models now that you put it all down! Thank you!

Thanks.  No problem.  Just my take...may or may not be correct.  Been an interesting season so far.  

[Chattownsnow]

Thanks carvers for all your analyses. I think that first system will cause problems for a lot of areas before the change over to rain as well. Cold air is dense and hard to move for sure. . Im just glad we have at least something to track still. I reshuffle of the cards was desperately needed in this pattern. It will be interesting to see where all this leads. 

[weathertree4u]

1 hour ago, Chattownsnow said:

Thanks carvers for all your analyses. I think that first system will cause problems for a lot of areas before the change over to rain as well. Cold air is dense and hard to move for sure. . Im just glad we have at least something to track still. I reshuffle of the cards was desperately needed in this pattern. It will be interesting to see where all this leads. 

Regardless, i will enjoy  a few days without  needing a fire. Already  burned more wood than lastvtwo seasons  combined, course, thats not saying much lol.

[PowellVolz]

I’m not convinced with the modeled temp profile for Sunday, Sunday night and Monday morning. If it’s 13ish Sunday morning, it would take a pretty strong system to WAA our area to make 40 degrees and if the WAA is that strong, I definitely do not see us falling off that night to the upper 20’s. I have nothing to back this up but that just seems strange to me.


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[jaxjagman]

ECMWF Deterministic FORECAST FOR: BNA    LAT=  36.12 LON=  -86.68 ELE=   591

                                            00Z JAN05
                 2 M     2 M     2 M     SFC     SFC    6 HR    FROZN   TOTAL
                 MXT     MNT     TMP     DEW     WIND    QPF     PCP    CLOUD
                 (F)     (F)     (F)     (F)    (KTS)   (IN)    (IN)    (PCT)
FRI 00Z 05-JAN                  17.3     0.6    31004   0.00    0.00       0    
FRI 06Z 05-JAN  17.4    14.5    14.4     0.0    32003   0.00    0.00       1    
FRI 12Z 05-JAN  15.9    13.9    15.1    -0.7    28002   0.00    0.00      37    
FRI 18Z 05-JAN  27.0    14.3    27.2     0.0    31005   0.00    0.00      68    
SAT 00Z 06-JAN  29.7    22.9    23.5     5.6    36005   0.00    0.00       0    
SAT 06Z 06-JAN  23.5    17.6    17.5     2.6    03004   0.00    0.00      16    
SAT 12Z 06-JAN  17.5    13.0    12.9    -2.6    02004   0.00    0.00       0    
SAT 18Z 06-JAN  27.1    12.2    27.3   -12.4    01003   0.00    0.00       0    
SUN 00Z 07-JAN  30.0    22.3    22.4    -8.2    05004   0.00    0.00       0    
SUN 06Z 07-JAN  22.8    20.2    20.2    -8.0    12005   0.00    0.00       1    
SUN 12Z 07-JAN  22.3    19.8    22.4    -5.4    16006   0.00    0.00      98    
SUN 18Z 07-JAN  40.4    22.3    40.7     1.0    17008   0.00    0.00      99    
MON 00Z 08-JAN  45.3    39.0    39.0     9.4    17009   0.00    0.00     100    
MON 06Z 08-JAN  39.1    36.5    37.5    21.9    18013   0.02    0.00     100    
MON 12Z 08-JAN  37.6    34.7    36.8    34.7    19011   0.07    0.00     100    
MON 18Z 08-JAN  40.6    36.7    40.4    39.7    21004   0.06    0.00     100    
TUE 00Z 09-JAN  41.5    36.0    36.7    36.5    12002   0.03    0.00     100    
TUE 06Z 09-JAN  37.1    35.2    36.0    35.9    05002   0.01    0.00     100    
TUE 12Z 09-JAN  36.7    35.3    36.6    36.5    04004   0.00    0.00     100    
TUE 18Z 09-JAN  42.2    36.5    42.3    41.6    05003   0.00    0.00     100    
WED 00Z 10-JAN  44.3    41.5    41.5    41.1    06004   0.00    0.00     100    
WED 06Z 10-JAN  43.3    40.3    42.9    42.6    14004   0.01    0.00      58    
WED 12Z 10-JAN  45.2    41.5    44.5    44.4    16006   0.00    0.00      80    
WED 18Z 10-JAN  57.4    44.5    57.7    53.4    17010   0.00    0.00      95    
THU 00Z 11-JAN  59.5    54.1    54.0    51.3    16009   0.00    0.00      97    
THU 06Z 11-JAN  54.3    52.7    53.7    51.1    16010   0.00    0.00      99    
THU 12Z 11-JAN  54.1    52.0    52.6    51.6    15007   0.05    0.00      99    
THU 18Z 11-JAN  57.0    52.3    56.9    56.1    18007   0.38    0.00     100    
FRI 00Z 12-JAN  57.2    54.3    54.3    54.2    17005   0.16    0.00     100    
FRI 06Z 12-JAN  54.3    49.7    51.3    51.2    30004   0.57    0.00     100    
FRI 12Z 12-JAN  52.5    38.2    38.1    37.6    33011   0.67    0.00     100    
FRI 18Z 12-JAN  38.1    36.7    37.3    35.7    35011   0.01    0.00     100    
SAT 00Z 13-JAN  37.4    32.6    32.5    31.5    36012   0.09    0.01     100    
SAT 06Z 13-JAN  32.5    31.0    31.1    30.1    34011   0.58    0.11     100    
SAT 12Z 13-JAN  31.1    27.3    27.3    24.3    30010   0.77    0.76     100    
SAT 18Z 13-JAN  31.9    26.5    32.2    16.1    29007   0.02    0.02       0    
SUN 00Z 14-JAN  36.6    30.7    31.2    23.8    28006   0.00    0.00      31    
SUN 06Z 14-JAN  31.3    24.8    24.7    16.9    33006   0.00    0.00      47    
SUN 12Z 14-JAN  24.7    19.1    19.1    16.0    32005   0.00    0.00      15    
SUN 18Z 14-JAN  28.4    17.6    28.6    18.5    34005   0.00    0.00      26    
MON 00Z 15-JAN  30.6    21.5    21.3    16.4    00004   0.00    0.00       0    

[PowellVolz]

Jax am I reading that right, that between 6z and 12z Sunday the temp goes from 22 to 40?


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[jaxjagman]

7 minutes ago, PowellVolz said:

Jax am I reading that right, that between 6z and 12z Sunday the temp goes from 22 to 40?


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You must have read it wrong,that would be 12z to 18z it does that

[jaxjagman]

3 minutes ago, *Flash* said:

Finally! We are not shut out in the frozen QPF department.

Yeah but more than likely it will be what we've seen all winter thus far,the next run it will go "poof"

[PowellVolz]

You must have read it wrong,that would be 12z to 18z it does that

So I just got my times wrong correct? I’m not saying that’s impossible but that’s some strong WAA in this air mass we’re in now.


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[Bango]

43 minutes ago, PowellVolz said:

So I just got my times wrong correct? I’m not saying that’s impossible but that’s some strong WAA in this air mass we’re in now.


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I am with you, cold entrenched air of the magnitude we have had is often not handled well with models (2014-15 was a similiar example of bitter cold being slow to dislodge).  Yet it looks like the storm is now rolling in monday rather then late sunday (if at all)...

[nrgjeff]

1. Sunday night: Strong southwest flow all the way to the surface is forecast with surface HP in full retreat. I could see ice up on the Plateau, parts of Eastern Kentucky, and high valleys of the Apps. I'm counting on all rain in Chatty. However, very cold ground is being considered even if the temp is 33-34.

2. Late next week bowling ball: I believe it will track up the existing slowly moving front. Possible set-up for the Mid-South and/or Kentucky. I'll go rain in the Tennessee Valley proper.

3. February: I remain confident, or even a touch more confident, that it will turn cold again. CFS seems stuck in the warm pattern. Euro weeklies re-introduce the Northeast Asia trough by Feb. Should build Alaska ridge. PNA might start backwards, even with -EPO, so cold pattern would evolve slowly for us. Analogs (assuming AK fcst) have cold getting in here in Feb.

Until then, talk to everyone again in 3 weeks. Just kidding; have a good weekend!

[Carvers Gap]

12z GFS/CMC have the second system as a far inland runner...some may call it an Apps runner.  Looks like the energy is going up the east side of the Apps.  Jeff, do you think we are rain due temp profile and/or the proximity of the slp being too close and weak?  Seems like the Plateau and westward might have a shot just speaking verbatim of the 12z GFS/CMC runs, even w the 0z Euro setup.    Was a slight reflection of the slp in the eastern Valley, which would sour any temp profile here.  Definitely can see temp problems on both models...but if that system were to run east of the Apps and deepen, wouldn't that be a plus?  So much energy in the approaching trough that it seems like the models are having difficulty w "deciding" which piece to accentuate.  Thanks for your comments!

[PowellVolz]

EPS temps today for Knoxville are not even close. Mean high temp is 30, the lowest temp was 27. I’m at 19 at my house. Euro op high was 29. GFS was 28.

 

 

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[Jed33]

7 minutes ago, PowellVolz said:

EPS temps today for Knoxville are not even close. Mean high temp is 30, the lowest temp was 27. I’m at 19 at my house. Euro op high was 29. GFS was 28.

 

 

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Clouds are really keeping a lid on the temps. MRX mentioned in the AFD that sky cover would be more pessimistic today. However they weren’t going to adjust the high temps?? Looks like we’ll be doing good to gain 3-4 more degrees if the clouds do hold on. If not, then maybe. 

Meanwhile, look at the 12Z Euro dropping that low almost down to the Yucatán??!!! How in the world!! I’ve never seen that. I just can’t imagine that will verify. We are talking about the once “mighty” king here though. It’s struggling this year.

[Carvers Gap]

14 minutes ago, Jed33 said:

Clouds are really keeping a lid on the temps. MRX mentioned in the AFD that sky cover would be more pessimistic today. However they weren’t going to adjust the high temps?? Looks like we’ll be doing good to gain 3-4 more degrees if the clouds do hold on. If not, then maybe. 

Meanwhile, look at the 12Z Euro dropping that low almost down to the Yucatán??!!! How in the world!! I’ve never seen that. I just can’t imagine that will verify. We are talking about the once “mighty” king here though. It’s struggling this year.

In all seriousness...is that on any other model?  It impacts this run heavily by getting entrained in the second system.  The GFS is slow to move it OTS, but does move it.  CMC kicks it along as well.  The Euro has had this for three straight runs. This run, it actually gets brought back in....

[Jed33]

Would be pretty rare imo if that actually happened like that. Seems like it would end up making a powerhouse of a storm. I can’t see anything but the free maps though, so I don’t know.

[Carvers Gap]

12 minutes ago, Jed33 said:

Would be pretty rare imo if that actually happened like that. Seems like it would end up making a powerhouse of a storm. I can’t see anything but the free maps though, so I don’t know.

Like 12z yesterday...not easy to describe.  Sort of wonders around the GOM, then gets picked up, and becomes the lead energy of the second system.  Pretty sure no other model has even remotely that.  The run really suffers after system one gets pulled from the Yucatán back into the system.  Now, the bomb cyclone did something similar off the SE coast of FL.  Maybe there is a back eddy in the jet right now.  That does happen sometimes.   And yes, if that got left back...look out Ohio.  I mean, I was half expecting a tropical storm to develop....just checked the UKMET.  It stalls system one near Cuba.  It looked like it would become a cutter.  But tough to tell on that model at 24 hour increments.  Till that gets worked out, just a guessing game for me.  I will still roll w a system through the Piedmont or just west of that.

[Carvers Gap]

Seems like a consolidated slp makes more sense without the static of low #1.  How strong it gets, path, etc....TBD.  The Euro looked too strung out due to the second system. IF the 12z Euro is correct,  I just don't see lightning striking twice in the same spot.

[jaxjagman]

Euro looks like a big long wave,5H don't close off like last night,no bowling ball.So we go from around 8-9" to .01"...lol

[nrgjeff]

Euro and EPS notes: Yucatan to Florida shortwave should impact the first system anyway. Our system of interest is the second one. I still think it's cold chasing rain. 8 days out my reasoning is mainly pattern recognition and default skepticism. Even if the first system is stronger, more CAA behind, it would also have subsidence and upper-level confluence behind it - bearish for the second system.

Again the Euro nailed the cold dry regime. Despite a few minor details on December tracks, it's doing fine this year. Euro is the undisputed king of patterns. I listed the clean sweep of all categories for the Euro in a post last week. If I could have only two models it would be the Euro and one short-term hi-res (maybe the ARW version of the WRF for severe). As for the GFS, where is all that ice forecast 2-3 times?

My Christmas Day post: European model from the ECMWF is superior for several reasons. ECMWF has the best verification numbers by statistically significant and wide margins, all regions all levels all layers of the atmo. Euro does not make wild pattern swings every six hours. Euro biases are known; therefore, one can always use it as a valuable tool. Euro accuracy is almost a day better than that of the GFS. In other words Euro Day n+1 beats GFS Day n. Euro is not perfect though, late to December 8. However it appears to have handled the current week.

Everyone enjoy the playoffs this weekend. Chiefs and Titans makes fun times!

[Carvers Gap]

18z GFS Happy Hour run is a thing of beauty for middle and west TN.

[John1122]

18z NAM just dies with the first storm Monday. At this rate eastern areas may not even get rain. 

[John1122]

That GFS run bullseyed me with about 1.2 inches of freezing rain. I have found that in situations like that the freezing line is normally further south and east than modeled. The warm air banks up on the east side of the valley and it might be 50 in Newport but it's 31 in Oliver Springs or Rockwood. 

[John1122]

1 minute ago, John1122 said:

That GFS run bullseyed me with about 1.2 inches of freezing rain. I have found that in situations like that the freezing line is normally further south and east than modeled. The warm air banks up on the east side of the valley and it might be 50 in Newport but it's 31 in Oliver Springs, Tazewell or Rockwood. 

 

[John1122]

I don't know how I posted and posted a quote of myself up there.

[PowellVolz]

That GFS run bullseyed me with about 1.2 inches of freezing rain. I have found that in situations like that the freezing line is normally further south and east than modeled. The warm air banks up on the east side of the valley and it might be 50 in Newport but it's 31 in Oliver Springs or Rockwood. 

I agree John. I think it was 2015 when a similar setup of a storm chasing retreating cold air. The mods and Mets said a little snow to sleet to RZ to rain and by afternoon it would be gone. It started snowing and only briefly changed to sleet at the end. 6” later it was still 29 degrees. I remember looking at opps in the mountains and Ober had mostly rain in the mid 30’s.


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[Jed33]

Remember that one so well. One of my favorite snow storms!

[John1122]

53 minutes ago, PowellVolz said:

I agree John. I think it was 2015 when a similar setup of a storm chasing retreating cold air. The mods and Mets said a little snow to sleet to RZ to rain and by afternoon it would be gone. It started snowing and only briefly changed to sleet at the end. 6” later it was still 29 degrees. I remember looking at opps in the mountains and Ober had mostly rain in the mid 30’s.


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Warm air banks over there and it really floods in above 3500 feet or so. You'll see Newfound Gap at 55 and Knoxville in the lower 30s at times like that.