Winter Speculation 17/18 -December Thread

[PowellVolz]

MRX still isn’t sure what to expect. Sounds like they are starting to get concerned over the snow situation.

“DISCUSSION...Strong southwesterly winds this morning is pulling
warmer air into the region. Temperatures are already climbing
through the 40s. Have upped high temperature for most of the
location.

Very strong 300mb jet of nearly a 170kts will move across the Ohio
Valley later today and tonight. This is an abnormally strong upper
jet with the upper forcing associated with the right entrance
region quite strong. This jet forcing will quickly strengthen the
frontal-genetic along a boundary moving southeast into Kentucky.

Models continue to show strengthening fronto-genetic forcing
rapidly developing precipitation over kentucky this afternoon,
then moving into the area by late afternoon and evening. The
precipitation type is the tricky part as initially the boundary
layer temperatures will be relatively warm, but strong diabatic
cooling due to the strong forcing will quickly cool the vertical
column.

A fairly quick change over from rain to snow will occur this
evening. The questions are the following:

1) How fast will the change over occur?
2) How fast will snow accumulate after transition?
3) How long will accumulating snowfall last?
4) Snow will initially accumulate on the grassy areas, but
how soon on the roadways?

After looking at new NAM/RAP runs and SPC SREF snowfall plumes
have decided to extend the advisory to the Plateau and northeast
Tennessee for now.”


.

[John1122]

From my understanding of the MJO, there is a trough in the East 2 weeks after it passes through 4-5-6. This according to some NOAA papers I've read. It's about to complete the 4-5-6 cycle this week.

Quote

Conversely, two weeks after the MJO passes through phases 4, 5, and 6, there is a trough over the East Coast and anomalously cold temperatures. These patterns occur primarily during the winter months.

 

 The GEFS seems to have it dying in phase 7. The analogue forecasts have it passing through Phase 8 at various amplitudes. 

So based on 2 weeks post 4-5-6, a -EPO/+PNA/-AO forecast plus possibly phase 8 MJO or the MJO in the CoD I don't really see many reasons to think that super warmth would verify in week 2+ 

Today's 12z GEFS suggests below normal temps days 1-5, 6-10, and 10-14 in the East. If the MJO phase 4-5-6 to trough in the east 2 weeks later comes to pass, it should remain cold in the East beyond day 14. I usually prefer to wait and see what the Pacific looks like though. It stomps all over the MJO as we learned last year. It crushed the 4-5-6 rule and we got no trough and it smoked phase 8-1-2 and we got no cold. There was that unshakable +EPO/-PNA combo.

[TellicoWx]

51 minutes ago, PowellVolz said:

MRX still isn’t sure what to expect. Sounds like they are starting to get concerned over the snow situation.

“DISCUSSION...Strong southwesterly winds this morning is pulling
warmer air into the region. Temperatures are already climbing
through the 40s. Have upped high temperature for most of the
location.

Very strong 300mb jet of nearly a 170kts will move across the Ohio
Valley later today and tonight. This is an abnormally strong upper
jet with the upper forcing associated with the right entrance
region quite strong. This jet forcing will quickly strengthen the
frontal-genetic along a boundary moving southeast into Kentucky.

Models continue to show strengthening fronto-genetic forcing
rapidly developing precipitation over kentucky this afternoon,
then moving into the area by late afternoon and evening. The
precipitation type is the tricky part as initially the boundary
layer temperatures will be relatively warm, but strong diabatic
cooling due to the strong forcing will quickly cool the vertical
column.

A fairly quick change over from rain to snow will occur this
evening. The questions are the following:

1) How fast will the change over occur?
2) How fast will snow accumulate after transition?
3) How long will accumulating snowfall last?
4) Snow will initially accumulate on the grassy areas, but
how soon on the roadways?

After looking at new NAM/RAP runs and SPC SREF snowfall plumes
have decided to extend the advisory to the Plateau and northeast
Tennessee for now.”


.

Good write-up from MRX, if the SREF and NAM don't change on their next runs, wouldn't be surprised if they added Blount/Loudon north to the WWA just to be cautious due to the potential of roads icing up in spots overnight. Seems this may be a year in which we 1" it to death to get close to normal snowfall.

[TellicoWx]

28 minutes ago, John1122 said:

From my understanding of the MJO, there is a trough in the East 2 weeks after it passes through 4-5-6. This according to some NOAA papers I've read. It's about to complete the 4-5-6 cycle this week.

 

 The GEFS seems to have it dying in phase 7. The analogue forecasts have it passing through Phase 8 at various amplitudes. 

So based on 2 weeks post 4-5-6, a -EPO/+PNA/-AO forecast plus possibly phase 8 MJO or the MJO in the CoD I don't really see many reasons to think that super warmth would verify in week 2+ 

Today's 12z GEFS suggests below normal temps days 1-5, 6-10, and 10-14 in the East. If the MJO phase 4-5-6 to trough in the east 2 weeks later comes to pass, it should remain cold in the East beyond day 14. I usually prefer to wait and see what the Pacific looks like though. It stomps all over the MJO as we learned last year. It crushed the 4-5-6 rule and we got no trough and it smoked phase 8-1-2 and we got no cold. There was that unshakable +EPO/-PNA combo.

I remember a poster a long time ago in the old TalkWeather forum who was really great with MJO and analog data. He covered mainly around the Atlanta area. A lot of his analog data would show a very low amplication or even COD produced more significant snowfalls for Atlanta area historically than people realised. Wished I would have saved some more of his stuff now.

[TellicoWx]

You can see on radar what MRX was talking about with the precipitation intensifying as the forcing becomes stronger. Front is currently beginning to cross the Kentucky/Indiana line with the precip field growing and intensifying along it.

[tnweathernut]

On 1/30/2018 at 3:50 PM, ShawnEastTN said:

 

[John1122]

21 minutes ago, TellicoWx said:

You can see on radar what MRX was talking about with the precipitation intensifying as the forcing becomes stronger. Front is currently beginning to cross the Kentucky/Indiana line with the precip field growing and intensifying along it.

JKL said it was increasing snowfall totals for both it's NW and SE areas due to to this. Whitley Co, where Kentucky is from, and my northern border county, has a forecast of 1-3 inches this evening after their afternoon update.

[nrgjeff]

Strong MJO pulse with current high global wind is a warm signal, contrary to the generic phase 7-8.

1 hour ago, John1122 said:

From my understanding of the MJO, there is a trough in the East 2 weeks after it passes through 4-5-6. This according to some NOAA papers I've read. It's about to complete the 4-5-6 cycle this week.

12Z suite is on fire. I did not expect that when I wrote my original post.

ECMWF weeklies may be painful tonight. Guess we can hope around Feb. 20 but then we start fighting climo.

[Carvers Gap]

OK...hype or truth?  I realize the source, but interesting if true.  I am not not in the "winter is over" camp yet, though I dabbled my toe in it last night.  But somebody had to say it in order to break the bad mojo.   So if winter comes back, Jeff gets a ChopHouse gift card.

 

[Carvers Gap]

8 minutes ago, nrgjeff said:

Strong MJO pulse with current high global wind is a warm signal, contrary to the generic phase 7-8.

12Z suite is on fire. I did not expect that when I wrote my original post.

ECMWF weeklies may be painful tonight. Guess we can hope around Feb. 20 but then we start fighting climo.

Weeklies will be ugly...ugly...ugly IMHO.   Still uncertain about the MJO being right on the models.  Definitely uncertainty there.  

[John1122]

I'll take my chances on cold with these looks. It may be proven wrong but I've never seen the Pacific look this favorable and it torch here. Not to mention the AO absolutely tanking into oblivion.

For reasons beyond me the EPO map won't post, but the EPO goes negative and stays in the -200 to -300 range for the first two weeks of February.

[Carvers Gap]

The end of the 12z Euro run was not a bad look IMO....certainly better than this AM where the trough lifted out.  

[John1122]

11 minutes ago, Carvers Gap said:

Weeklies will be ugly...ugly...ugly IMHO.   Still uncertain about the MJO being right on the models.  Definitely uncertainty there.  

The weeklies are really doing poorly lately. Your breakdowns over the past few weeks shows that. They are ice box to end of winter from run to run. I don't remember if it was here or another poster in the SE forum who mentioned the repeat rule and that we were basically looking at a pattern repeat of late December into January coming up soon. The indicies bear this out with the PNA/EPO/AO combination. 

[jaxjagman]

24 minutes ago, Carvers Gap said:

OK...hype or truth?  I realize the source, but interesting if true.  I am not not in the "winter is over" camp yet, though I dabbled my toe in it last night.  But somebody had to say it in order to break the bad mojo.   So if winter comes back, Jeff gets a ChopHouse gift card.

 

The GEFS shows a split but slower doing it by a couple days

 

http://www.atmos.albany.edu/facstaff/andrea/webmaps/realtimeVortex/GEFSellipseFcast.html

[nrgjeff]

GFS can't decide which hemisphere to put the +/- anomalies, lol! Literally it moves them a continent each run. As for the December to January evolution, this is very different. We have a record MJO blowing more hot air into the mid-latitudes than Congress plus a positive global wind.

My Japan satellite Kochi University is not updating but the China Met Admin is updating. It does not include the equator, but it looks like the West Pac is blowing up even more than the last photo from Kochi U. East of the Philippines looks like summer!

[Carvers Gap]

I will add...it does seem when we have to talk about the MJO and SSTs that things are less than optimum in our pattern.  LOL.  Those are like the last drops of water in a hot desert. 

[Carvers Gap]

From MRX regarding Sunday....

A weak shortwave moving through the trough will cause widespread
showers to begin late Saturday night into Sunday morning. A weak
upper level jet will allow strong convergence through the early
morning...combined with PW values close to the 90th percentile for
the area...will cause widespread moderate showers. Models have been
inconsistent with temperatures at the surface Sunday morning...with
the most recent model run showing temperatures near or above
freezing through the night and early morning. Could expect some
cooling through the lower levels to take place as the snow starts to
fall...allowing for snow flurries to be seen across the area...but
at this time not anticipating any measureable snowfall accumulation
totals in areas south of I40 and only about 1 to 2 inches in areas
north of I40. Temperatures will quickly climb into the upper 30s
through the morning...with any snowfall transitioning to rain.
Models also disagree on temperatures in SW NC...where enough of a
warm mid level inversion could cause the possibility of freezing
rain for a couple of hours around sunrise. A weak mid level jet will
move through the area early Sunday morning with gusty winds possible
of 30-40 mph.

[jaxjagman]

Models are having a tough time in Asia also.Look at China and Mongolia yesterday.China was trying to build a ridge and heights rising into Mongolia.Today it's totally flip-flopped with heights beating down  in China with a trough into Mongolia

[Carvers Gap]

As expected...the Weeklies are torch city.  Winter does return though...in mid-March.  Fake-out February to be replaced by Marvelous March.  Do I believe them?  Maybe, maybe not.  Right now the models have flipped flopped from cold to warm to cold and now warm again.  The answer is probably somewhere in between.  It is likely that Feb finishes AN, but February generally holds surprises.  Really not worth going through the entire cluster of solutions.  Weeks 4-6 is colder.  I do not think our snow chances are over, but they will be severely limited.  Instead of a 6-8 possession half of football, we may be down to 2-3.  Need to make them count...Now, the silver lining...man, it is bowling ball after bowling ball after bowling ball on the control.   And some of them do form big storms.  How wild would it be to have a base warm state with big EC snows?

[jaxjagman]

[jaxjagman]

You can see a wind reversal on this chart for a SSW.If the blocking can hold on we could see a -NAO for awhile with colder air into the NA,that would have ramifications with the weeklies down the road.Still a big IF.But the Euro shows it now.

[jaxjagman]

Nice spike at the temps on the  pole on tonight's JMA,should go up tomorrow

[jaxjagman]

Looks like a viscous tube cloud is going to destroy the Central plains into Canada...lol.Good grief GEM,you can't get any worse.obviously some feed back problems,or is it just crap?ns io 

 

[Carvers Gap]

I feel like I have seen this movie before.  The Euro OP deepened the d8-10 trough.  The EPS at d14-15 now has a trough where there was a NA monster heat ridge on yesterday's runs.  The GEFS at 0z is slightly BN throughout its timeframe w a few warm interludes.  

[kvskelton]

54 minutes ago, Carvers Gap said:

I feel like I have seen this movie before.  The Euro OP deepened the d8-10 trough.  The EPS at d14-15 now has a trough where there was a NA monster heat ridge on yesterday's runs.  The GEFS at 0z is slightly BN throughout its timeframe w a few warm interludes.  

Well Carvers, it IS Groundhog Day after all! 

[Wulfer]

Well, it sounds like the groundhogs know something the models don't.

[Carvers Gap]

28 minutes ago, kvskelton said:

Well Carvers, it IS Groundhog Day after all! 

It did after all just snow during my forecasted warm-up.

[Carvers Gap]

Sometimes you come across posts in other forums that are just too good not to share....remember to click the white text in the gray header.

 

[nrgjeff]

I have zero interest in the Super Bowl event down in Chattanooga. Rainy days are great for watching football on TV.

The SSWE is forecast to impact Eurasia, which is no surprise. Peer reviewed research shows a correlation for Eurasia but little to none for NA. Weeklies (CFS/ECMWF) today are in good agreement that China will celebrate the Spring Festival too early this year. SF is even late due to the lunar calendar, but China looks cold anyway.

I will assume the European weeklies are right for the USA. This is my last post of the thread barring another major flip. Look for me in Severe Weather 2018.

[Carvers Gap]

SOI is crashing.  That is a good sign.  From the Longpaddock site.  Agree with Jeff that the SSW is not a given to impact our weather in a positive way, but I am pointing out there may be a new driver in the northern hemispheric circulation pattern.   Given the craptastic look on the EPS for the past 5-6 runs, I will take a reshuffle even if there is sketchy correlation.  I can't see the Euro MJO today, but JB reports that it is at odds with its own forecast.  I will wait and decide for myself. Updated...indeed the CPC MJO site is updated.  The ECMWF does look like it will go into phase 8.  The EMON goes into phase 8 at low amplitude and then does the COD deal.  The JMA, which has been steady, goes phase 8.  The CFS stalls in phase 8. Interestingly, the American model suite did decently well with that crazy MJO forecast that it had.  Surprised me for sure.  The EPS is out on a limb IMO with the GEPS and GEFS not being nearly as warm.  I definitely can see how the EPS would be right, and to go against it is at risk to personal mental injury.  But I am a glutton for punishment.  A week or so ago, I backed away from my cold thoughts and then went warmer.  Then, I went back in the cold camp w the EPS.  Now, it is warm.  I think it is just time to quit flip flopping on my part.  So, I think I am going to stick w/ the cooler look for a few days and see if things come back around while knowing that I may be on shaky ground.  Plus, it is overly boring to agree all of the time.  The CPC ensembles do show a decently positive PNA and sharply dropping AO.  Those have been a decent benchmark over the years while certainly not infallible. If those flip, then warm I go.  But right now, those are a strong cold signal w a somewhat strong downturn of a decently positive NAO(not to negative BTW).  Finally, let there be no mistake, the EPS has a decent chance of being correct, but there are some strong counters to its solution not to mention that it did a check swing on the torch at d14-15.  As for severe wx...I am a huge believer in this saying, "When there is thunder in the mountains during winter, it will snow within two weeks."

One addendum...notice the differences with the Euro MJO vs the field.  The Euro MJO stalls in phase 7 where the others move quickly through it.  Also note that the Euro MJO makes two quick strides into 7 now and then stalls.  It completely missed the high amplitude of phase 7.  I have no reason to believe it is correct now...other than it is a bad look for us and that is more likely to verify than not.   

 

Here are a couple of Mike Ventrice tweets.