Re: Long Range Thread 12.0

[frank 638]

We really do need this pattern change because our drought is getting worse and worse we might have a mini nor easter on wed

[Dunnzoo]

are we really looking at possibility of snow over thanksgiving?

It looks like some precip a few days before Turkey Day, but it does look like it will be cold...

[sroc4]

are we really looking at possibility of snow over thanksgiving?

It looks like some precip a few days before Turkey Day, but it does look like it will be cold...

I certainly wouldn't write off anything in the long term but I agree with Janet. There will likely no be enough cold air around to support snow.

[sroc4]

Ill tell you what though there are big changes amis; specifically regarding the SST anomalies.  I have been looking at everything from the surface to the stratosphere and the potential linkages between all of them, but the write up I ideally want to do will likely take way too much time for today.  I know this is all very vague so to just give you an idea of what I'm thinking...take a look at this:

These are the Global Sea Surface Temp Anomalies (SSTA) from This morning followed by Sept 7th; then June 15th 2016 .  Pay particular attention to three things.  1) What prob stands out the most is the N Pac.  In only two short months our nice warm "blob" of strong SSTA in the GOA have been eroded significantly because extremely cold SSTA have developed and expanded eastward undercutting the blob.  2) notice how the cold SSTA have spread westward in the ENSO region in the Trop Pac and 3) notice where the SST across the globe are going.  For instance look at the S Atlantic between S America and Africa, look at the N Atlantic and off the EC of the US, the Trop Pac, the IO, the N Pac from June till now.  As a whole the entire global SST are cooling the effects of which could be profound in the coming years on global air temps as whole if this trend were to hold.  





Here are the SSTA changes over the last 7 days which shows the SST cooling globally:



Now if you recall the reason we like the warm blob in the NE Pac/GOA is because the temp gradients between SSTA tend to favor ridging that extends up into Alaska and the West coast of Canada and the CONUS (-EPO and +PNA respectively) when you have that warm blob in the GOA.  However; as you can see the strongest temp gradient is set up in a distinct horizontal fashion from west to east, but is no longer strongest near the GOA.  Now notice there is the warmest SSTA of the N Hemispheric Pac ocean smack dab in the center of the Pac due south of the prev described cold anomalies.  It is right here in this location that we have the greatest differences in the SSTA.  NOTE: If this SSTA configuration conts into the winter it might spell disaster without other large scale pattern changes to help us out.  Things like a strong MJO pulse in favorable phases or a strat warming event to name a couple.



Likely NOT coincidentally an HP ridge is centered in the Central Pac and due north is the exceptionally strong N Pac jet.  Here is 500mb followed by 250mb.  But also notice how the lower atmosphere(tropospheric circulation) seems to be lined up with the stratospheric circulation (70mb and 10mb).

Following maps are 500mb, 250mb, 70mb, and 10mb respectively:







Now we began this discussion at the surface regarding the SSTA and have worked our way up.  But if we now re-start at the top, in the Stratosphere, there other extremely interesting observations.  I unfort don't have time this morning to go into those details, but as we know we had an unprecedented SSWE and split that has occurred.  You've prob heard multiple times about how the coldest air in the N Hemisphere has been locked up and centered over in Asia and eastern Europe.





When you look at the positioning of the stratospheric circulation from the view point of overtop the arctic circle you can understand why.  Unfort we will likely need the strat circulation to be positioned differently than it is currently in order to unlock the cold air in siberia and the arctic.  By unlock I mean reconfigure the tropospheric upper level pattern(500mb and 250mb) such that we get a cross polar flow which will filter that cold air down into Canada and eventually the CONUS.  Right now we have moderately cold air masses at best to our N which get mixed with warmer pacific air due to the prev described strong N Pac jet flooding the country with Pac air.  




This is where I must stop but will try to cont tomorrow am with those images and discussion.

[Frank_Wx]

I am not concerned about the cooling trend in the NPAC...yet. If you follow the cold anomalies they extend west-southwest toward the coast of Asia. This "path" of cold water was inundated with typhoons or deep low pressure systems over the last few weeks. We're now in or heading into a typical La Nina pattern, where the western U.S. will experience unsettled weather and we'll remain drier than normal with shots of cold air, but nothing sustained. Our pattern change is still ways off.

Fact of the matter continues to be the Stratosphere PV is very weak.



The lime green line is a mean of 10hPa temps between 1979 and 2015. Check out November 2016. The red line, which is current temperatures, is above the green line. So instead of the Stratosphere cooling, as is typically the case, it is warming at both the lower and mid levels. This makes it susceptible to a SSWE in the near future.





GFS long range shows a near PV split around Thanksgiving. The main vortex is over Siberia and another lobe is left over Greenland.

Here is what a record-breaking SAI (snow advanced index) in Siberia can do. The High's that develop are anomalously strong and promote poleward heat flux into the Stratosphere. That High in eastern Europe could be a possible precursor to a SSWE sometime late this month. GFS is close. We'll see.

[sroc4]

You are alluding to part two of my thoughts Frank.

[algae888]

Both the GFS and CMC show a tropical system next weekend affecting the East Coast and getting intertwined with a strong trough in the middle of the country. This could be a trigger to change the pattern as we go forward. Also I'm hearing the weeklies and other long-range guidance are showing a predominantly -AO. While this doesn't always mean cold weather during the fall there's a strong correlation to colder weather in December.

[amugs]

How about this for the Northern plains - this is what we Need to see moving forward.

[algae888]

How about this for the Northern plains - this is what we Need to see moving forward.

Mugs north Dakota temp dep is +16* so far for November and if the GFS is corrected that's 1 to 2 feet of snow

[amugs]

GEFS for turkey week - trough over NE - blustery and snow flakes flying?

[weatherwatchermom]

GEFS for turkey week - trough over NE - blustery and snow flakes flying?

love it!

[amugs]

AO going N

[algae888]

the period from the 20th to the 25th looking a little interesting on all global models with favorable tele conn.

[algae888]

looks like gefs gets rid of the bearing sea low and actually builds heights in epo region although transient. as we head further out bearing sea low tries to pop again but much weaker. maybe we can get the pac In our favor for a time...


-epo

-nao +pna -ao we need to watch this time frame.

+pna -nao continues

[algae888]

also temps look to be below normal starting around the 20th and lasting entire run...



look at the westward progression of the cold air over Eurasia

[amugs]

AL- JB harping on this calling it the slosh tub effect  A meterological theorum that has been proven but has not been taught for about a decade in schools. Why ?Ask the prof at the schools who teach this.
IF we get a cross polar flow with these temps yes they shall moderate but holy cannoli batman this air is ridiculously cold!

[amugs]

GEFS barking at the NAO and AO over the top blocking with a cross polar flow next week through the end of it run. We saw this 2 weeks ago for this time frame and it was delayed. Lets see this run consistency and then by the end of teh week and then we are game on

[amugs]

[amugs]

EPS - NAO block next week too

[amugs]

[amugs]

Blizzard for the Dakotas - YIKES!! Good we need snowpack overthere and above into CANADA

[amugs]

[HectorO]

You guys must be wearing me down. As much as I like nice warm comfortable weather, I'm actually looking forward to some cold temps. Maybe a little around Thanksgiving to help bring in that mood.

[Frank_Wx]

A pretty disconcerting look on long range guidance. Positive anomalies are bombarding Canada while low anomalies persist over the northern Pacific near the EPO/PNA domains. While we still see troughs dig into our area, the cold air is moderated because there is not a cross-polar that sources the air from the Arctic. Further, snow cover in NA is running well below normal compared to climatological levels. While it's good news in Siberia which may help rossby wave transfer into the Strat, keeping the PV weak, it would help to see the cold begin pushing south into Canada. Think of it as a step-down process. Once they get cold (as in below normal for there area cause Canada in general is always cold in the winter) then it may not be long until it hits us as long as the Pacific cooperates.

At the get together I felt Thanksgiving time frame could bring us a 3-5 day stretch of below normal weather. That still looks possible if the long range GFS comes to fruition. But again, it's moderated cold and not a true "blast." It will be tough to get a snow event out of something like that in a pattern like this. But this time of year with the low sun angle it may not take much so we'll have to see.

[Frank_Wx]

One thing we can hang onto: 10hPa winds in the Strat still showing a reversal by late November. Easterly winds signal a weakening Strat PV making it susceptible to experience a SSWE (sudden stratospheric warming event). Timing is critical. As winds reverse easterly, we hope there is tropical upward momentum that transfers warming into the Stratosphere whether by wave 1 or wave 2.

[Frank_Wx]

And as you can see, the EURO is predicting a warming event though I remain cautious as to the extent of the warmth. Verbatim this is a good look for us.

[Frank_Wx]

Seeing the Stratosphere makes me feel good about my call for an early winter (colder than normal December). But I do have concerns about how the rest of the winter could play out.

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