Re: Long Range Thread 12.0

[amugs]

^^ I was not comparing this month to teh ice age month of 2015 February JUSt answering a question as to what month was below like thi sone - comparatively speaking it is Feb 2015 - the cold departures this weeks cold snap Wed - Saturday are to be -15 to -20 from normal. That plus 3 will be wiped out greatly.

[amugs]

Yes i know we will not end up close to feb 2015. However I think -3 looks pretty good at the moment and maybe -5 if the EPO can deliver. There really isn't a month to compare this December to over the last several years if guidance is correct. just look at today's Euro, we're looking at negative 20 to 25 temperature departures the end of next week

Al is it me or we keep getting colder? The EPO went from slight N middle of teh week to now -3 SD

[nutleyblizzard]

Yes i know we will not end up close to feb 2015. However I think -3 looks pretty good at the moment and maybe -5 if the EPO can deliver. There really isn't a month to compare this December to over the last several years if guidance is correct. just look at today's Euro, we're looking at negative 20 to 25 temperature departures the end of next week

Al is it me or we keep getting colder? The EPO went from slight N middle of teh week to now -3 SD

Yes we are trending colder. The big question is it sustainable? I think it will be with the occasional warmups as the pattern reloads. The Euro monthlies are a very encouraging sign as it shows a cold and snowy regime.

[Frank_Wx]

The -EPO won't mean much because the ridge is not poleward. Look at the raging -PNA/+NAO/+AO. This looks like a moderate LA Nina pattern with the SE Ridge amplifying up the EC. This is December 19th, around the period I suspected it could get warm again.

http://www.tropicaltidbits.com/analysis/models/gfs-ens/2016120912/gfs-ens_z500a_namer_40.png

Now, it doesn't get WAY above normal because the ridging in Alaska persists. Most likely we're looking at normal temps but if storm system cut to our west temps departures could range +2 to +5

[sroc4]

The -EPO won't mean much because the ridge is not poleward. Look at the raging -PNA/+NAO/+AO. This looks like a moderate LA Nina pattern with the SE Ridge amplifying up the EC. This is December 19th, around the period I suspected it could get warm again.

http://www.tropicaltidbits.com/analysis/models/gfs-ens/2016120912/gfs-ens_z500a_namer_40.png

Now, it doesn't get WAY above normal because the ridging in Alaska persists. Most likely we're looking at normal temps but if storm system cut to our west temps departures could range +2 to +5

Its interesting that you post this now Frank because I was just looking into the updated ENSO status.  Interstingly enough the latest ONI actually dropped from -0.7 to -0.8.  That makes 3 consecutive overlapping months with La Nina ONI values.  By the strictest of definitions to characterize a true La Nina or E l Nino you must have 5 consecutive overlapping months below or above -0.5 or +0.5 respectively.  That however does not mean that La Nina conditions cannot be present.  Here is the latest discussion from the CPC Valid Dec 8th.  The next 3 month ENSO out look will be updated on the 15th.  

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

Summary:
La Niña conditions are present.*
Equatorial sea surface temperatures (SST) are below average in the central and
east-central Pacific Ocean.
La Niña is slightly favored to persist (~55% chance) through winter 2016-17.*

It will be very interesting to see if the cold really can come and actually hold. The majority of the telleconnections are trending poorly in the LR, but as I ve always said the LR tends to just be that. We shall see how they evolve once the heart of the cold is entrenched. Although the EPO is trending negative it seems to peek with late next week after which time both the EPO and WPO come back towards neutral/positve. Reload or product of the main drivers of the atmosphere is yet to be determined.

[amugs]

Look at this , GFS is on the Media hype train holy smokes.
Al like I said we are trending colder.
From Ventrice

[algae888]

The para gfs is lovely for the next 7-10 days. You can view it for free on tropical tidbits

[amugs]

My bday storm part duece!!

[Frank_Wx]

Next event we have to keep an eye on is the 15th. EURO last night showed a coastal grazing our area with steady snowfall.



GFS was out to sea



This a PV-driven event. Check out the location of the PV by Thursday morning. It is in southeast Canada. There is a ton of 500mb energy circulating the PV. All it takes is one piece to break off and phase with another vort from the Pacific.



Also important to note is it will be very cold. Snow ratios should be greater than 10:1, could be 15:1 or even 20:1 in N&W sections.

[amugs]

EPS saying this could be a very nice timeframe for the EC as well
PV in SE Can and a N EPO and Pos PNA as well as a slight N NAO with Scandinavian block to the east of Greenland

[jmanley32]

Here's hoping the coast gets a good storm thursday. It's only December often the coast doesn't do well until jf.

[skinsfan1177]

Exactly what I've been saying Jman we are spoiled

[jmanley32]

And last year no one saw snow until.jfm.

[track17]

So what is the deal with Thursday

[algae888]

So what is the deal with Thursday

Todays models are south except the cmc. Still time to trend better. Models should have a better handle on it in a couple of days

[jmanley32]

CMC has a nice event for Sat, the coast is very close to getting snow (northern areas se ALOT) with that too, GFS has it way west. Thursday looks like it may end up missing to the south but as Al said it could change.

[Frank_Wx]

We're in a time crunch to try and pull off snow event next week, because it does look like after the 21st or so we'll see the return of the SE Ridge. Many are familiar with the details to this point so not worth repeating. The Trop PV will retreat back to the N Pole, causing the AO/NAO to shoot positive. The EURO takes it to almost +5 SD which is pretty remarkable. Meanwhile, we're seeing upper energy from Siberia continuing to follow the PAC jet and dig into the western U.S. This is a great wintry pattern for Chicago and that part of the country. They're actually getting a foot of snow tonight.

It's been the 12th-20th for awhile now. Monday N&W will see a nice snow event, then attention turns to the 15th and 17th. The system on the 15th may get sheared out from the PV to our north. As the PV lifts north, that allows room for short waves to also come north and amplify with cold air in place. Like others, I agree the 17th is a better period to see a storm than the 15th.

[Guest]

We're in a time crunch to try and pull off snow event next week, because it does look like after the 21st or so we'll see the return of the SE Ridge. Many are familiar with the details to this point so not worth repeating. The Trop PV will retreat back to the N Pole, causing the AO/NAO to shoot positive. The EURO takes it to almost +5 SD which is pretty remarkable. Meanwhile, we're seeing upper energy from Siberia continuing to follow the PAC jet and dig into the western U.S. This is a great wintry pattern for Chicago and that part of the country. They're actually getting a foot of snow tonight.

It's been the 12th-20th for awhile now. Monday N&W will see a nice snow event, then attention turns to the 15th and 17th. The system on the 15th may get sheared out from the PV to our north. As the PV lifts north, that allows room for short waves to also come north and amplify with cold air in place. Like others, I agree the 17th is a better period to see a storm than the 15th.

  Cutters, followed by suppression followed by hope then more cutters.

[sroc4]

So just like I always try to caution when the LR pattern looks to change from warm to cold or cold to warm on a large scale the modeling is usually too quick to do so, because the main drivers are not quite ready to give up the drivers seat.  We saw a clear example of this in late Oct and early Nov.  Modeling clearly was hinting at a much colder pattern as a whole that if you believed the LR modeling was always about 10-14days away.  In late Oct it looked like the beginning of the change was around the Middle of Nov, but then really looked to come in and hold, at least for a little while, by around Thanksgiving.  Yes we had a cold shot and a snow set up around that time frame, but the cold did not come until after the first week of Dec. when all was said and done.  Point being LR modeling is often too quick when recognizing a change to the big picture, so we will have to see if going back to the warm east cool west idea is going to be too quick and maybe just MAYBE we get an extra week of snow chances out of the current pattern.  

So what's up with the pattern.  When talking about the pattern we always talk about "the drivers" vs the "enhancers".   Up through late Oct and all of November the drivers to the pattern as a whole were the results of an unprecedented stratospheric warming event in Nov that sent the weakened strat vortex to the Asian side of the N Hemisphere, and the weak La Nina trop forcing conditions with smaller enhancers involved.  So what's driving the pattern now?  Simply stated the -WPO (Western Pacific Oscillation) decide it wanted to take over the driver seat for a period of time.  The way it looks from my perspective is that the -WPO is like the teenage son in the back seat who convinced his parents to let him have a turn at the wheel.  The question is how long is Jr going to be driving?  I believe that the other main drivers will be back in the front seats once again.  Modeling thinks it might be as early as around the 20th +/- a few days, but again I caution changes like this are often modeled too quick so I think end of the month is more likely but we will see.  Now keep in mind just because we MAY fall back into a crappy pattern doesn't mean we wont have other "enhancers" take a turn behind the wheel, nor does it mean the drivers that bring us back to a crappy pattern cant or wont eventually become a driver for the better. (ie: stratosphere if we get another significant warming event in Jan).

Here is last nights EPS map valid for 00z today.  Basically the current 500mb conditions showing how the -WPO poleward ridging has led to the arctic air masses to be pinched off and sent southward into NA on a cross polar flow.  The cold in asia has been there since Nov because the weak strat PV has been sitting over there.  


 
Now for those who think the La Nina is done or officially collapsed hold the phone.  For at least the next month or so we will likely still see La Nina like conditions flare up, esp when other drivers or enhancers relax like we will likely see to the -WPO in the not so distant future.  La nina like Walker circulations, although have been weak, remain present in the background as seen by the OLR maps and current observations with convection over 120E and the lack of around the dateline.





SST despite abruptly warming over a two week period just as abruptly seem to be coming back down to nearly where they were; esp in Nino regions 3.4 and 3.


CURRENT SSTA:


LAST 7 DAY CHANGE IN SSTA:







The MJO has had little to no effect on the pattern as a whole as it has been in the COD for some time.  Forecasts indicate it may re-emerge in phases5/6 which are typical of La Nina years and ridging in the E CONUS.  That said I have been following the LR MJO forecasts for the last several weeks and there seems to always be hints of it coming out of the COD in the LR in one phase or another but so far it has remained there.  Basically this means the MJO has had little to no influence on the big picture over the last few weeks.  That said with other factors in the atmosphere changing the MJO might have a chance to flare up with a pulse and become more influential.  Well see



Now its really between days 5-10 that we see the collapse of the -WPO ridging.  Following the collapse of this ridge the N Pac looks to fall back to the same look it had in the month of November with abroad trough across much of the N Pac by about the 20th-23rd.  This brings us back to the screaming N Pac jet flooding the western CONUS with Pac air.  Again I hesitate to take the timing of all this as gospel.    
 








Lets just briefly look at the Strat forecasts as well.  Tom (Isotherm) has been predicting this for some time now and unfort its showing up on the LR projections finally.  That is the re-emergence and consolidation of the Stratospheric PV over the N Pole and it becomes incredibly strong.  This will likely lock up all cold over the arctic should it come to fruition, without any other external factors affecting the pattern down below in the troposphere. Again these images are days 12-15 so a lot can change.






I know it typically takes alot to change the pattern once it becomes entrenched, but I see too many neg indicators to sustain the below normal temps beyond late month.  It may take longer than is currently modeled to come back, warmer than normal NE, but it is coming once again because again I believe the -WPO poleward ridge is a mere teenager behind the wheel and the big daddy and momma will take back over the drivers seat.  We may have to hope that we get a strong strat warming event in Jan to disrupt the PV again to re shuffle the drivers.  Maybe Tom or Frank can give an updated status on this potential for January.  We still have a lot of winter to go so no need to hit the panic button, but expect a period of normal to above normal yet again.

[amugs]

JB's video said we have until about Dec 22nd and then capute until Jan.
SE Ridge takes over as we lose our PAC Block - forget the Atlantic it has been god awful since 2010-11 overall.
One thing is for sure though this weeks cold will be very impressive for this time of year at the from middle till about the 18th/19th.
No mechanism to lock in the cold -what a shame.

Friday morning

[sroc4]

With all the negative I posted above I will say this. There are some indicators in the Euro weeklies that the timeframe after the New year may feature a -NAO which could still get us back to N to below normal. And if there truly is a west based -NAO actual snow storm chances too. Whether is the EPO/WPO region and/or the NAO/AO region we need some kind of blocking to get the cold air to come down. Again its all long range so things can and will likely change. At least we have the next 7-10days to keep our minds off of things.

[docstox12]

With all the negative I posted above I will say this.  There are some indicators in the Euro weeklies that the timeframe after the New year may feature a -NAO which could still get us back to N to below normal.  And if there truly is a west based -NAO actual snow storm chances too.  Whether is the EPO/WPO region and/or the NAO/AO region we need some kind of blocking to get the cold air to come down.  Again its all long range so things can and will likely change.  At least we have the next 7-10days to keep our minds off of things.    

Yes, Doc, we do have a nice cold December which is great for the Christmas spirit.Frank mentions a possible event for the weekend coming and, as you suggested in your excellent write up above, the shift to milder may be delayed.In any event, even if it flips milder, there is a LOT of winter ahead of us and late Jan-late Feb is normally the big time producer for snow around here.

Glass is half full!!!!!!

[Frank_Wx]

At least it will be cold next week, but we're struggling getting a favorable storm track with the cold air in place. Frustrating.

[Frank_Wx]

@Doc - good write up. La Nina ain't fading so quickly. Strat PV will keep our AO/NAO for forseeable future, lack of Trop forcing, continuation of a -PNA.

Brutal.

[skinsfan1177]

I thought Euro WEEKLIES looked amazing what happened

[Frank_Wx]

The EURO Weeklies are worth dirt. Very very unreliable. The EURO, since it's upgrade, has never been the same model either.

[Frank_Wx]

At this point, I'm confident in saying New years and early January will be very warm.

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