Long Range Discussion 22.0

algae888 wrote:I should also add GEFS has below normal 850's day 9 thru the end of the run

Al id take anything you see beyond day 7-10 with a huge grain of salt.  Remember the evolution we were follwoing for Nov 17th?  What happened to the trough S of the Alutian islands that seemed likely, and what happened to the possible +PNA/-EPO couplet....transient:

GEFS




Euro ENS



There are still some questions about the PNA and EPO regions and the duration of which these features are around, but confidence is gaining on a +PNA, -EPO couplet is on the horizon.  As an FYI the AO and NAO appear to hover around neutral to slight negative as we head beyond the 7-10 day time frame.  It does appear there is at least some staying power to the BN to N temp regime in the NE, but time will tell.  




Well here is the current GEFS Ens(Euro is the same) for 00z Nov 17th.  As you can see there is a deep negative now over the WC of Canada and the north west CONUS.  The trough coming on the heals of tomorrows rain for next week has no staying power.  It gets booted by that energy crashing the coast and the result if the SE ridge immediately flexing 24hrs later.






Here is the next snap shot to follow.  So long as there is a negative showing up along the WC of Canada and NW CONUS the cold will be transient. 2-4 days then out. The question will be as the next cold shot swings through can we get a storm track that brings in the cold first vs the SE ridge means warm out ahead and the cold only on the heals of the frontal boundary. If we can lay down some snow pack into NE over the next few weeks hopefully the cold air masses become more dense and diff to scour out.  

Al I think Im the glass empty guy and your the half full guy. Between the two of us we have a full glass...lol I dont mean to be going against the grain here but I was thinking about writing up these thoughts anyway.

So Id like to comment this morning on the pattern over the next couple of weeks.  Right now it seems the single most dominate Oscillation is the WPO.  The other oscillations seem to be transiently or temporarily in their various phases or neutral; whereas, the WPO seems pretty entrenched in its negative phase(ridging) for the time being.  Lets define where the oscillations live geographically before moving on:



The image above is a snap shot of the current 500mb pattern.  Below is the same image.  I have to take a quick moment to acknowledge the two Als (Mugsy and Algae) because they have been talking about "the building of the cold air over Canada".  The way I see it this statement cant be understated in its importance as we head into December.  Let's talk about that.  

Focus now on the image below and the WPO region.  The orange colors indicate a strong ridge in this region(-WPO).  Recall ridging = high pressure and clockwise winds, and Troughing(blue colors) = Low Pressure and counterclockwise winds.  Now follow the arrows.  With the -WPO in place what you get is a cross polar flow that leads to very cold air building in the area defined by the thin black circle.



Now lets focus on the EPO and PNA regions.  The blue colors indicate a +EPO(trough).  Even though its not a strong +PNA(more appropriate the PNA is not negative), the ridging in the PNA region allows the cold air to bleed S and E into our neck of the woods as energy from the EPO region marches eastward.  BUT, because the EPO is positive it allows Pac energy to persistently/continually crash the N half of the west coast(WC) of North America(NA) which flattens the ridging in the PNA region; keeping things in a bit of a transient pattern.  In the image below notice the linkage between the negatives(blue colors).  



So basically the current pattern is such that over the next couple of weeks you get waves of energy from from the pacific coming into the west coast of Northern NA, flattening the ridging in the PNA region.  As it heads east, ridge in the PNA region goes back up(albiet weakly), which allows the energy to then drop into S central Canada and the northern plains.  While this is happening the next piece of Pac energy(as you can see in the image below) is crashing the WC of northern NA which flattens the PNA yet again.  The flattening of the PNA allows the Polar energy to interact with the energy in the subtropical jet early which leads to a storm track less than ideal.  ie: SE ridge flexes a tad, we get warm sectored out ahead of the storm, we get rain followed by the cold air coming in behind it.  Rinse, wash, repeat for the time being.  




But here is the thing.  A storm track and pattern like this will lead to the building of the snow pack in the region outlined below.  Again going back to "the building of the cold air over Canada" statement above cant be understated.  BECAUSE, as the snow pack builds, so will the ability of the cold air to infiltrate further and further south and east.  Cold air is much more dense than warm air and eventually we will get cold air to bleed far enough s&E such that the interactions between the Polar and sub tropical energy will be late enough to bring snow into the region.  Obv it starts with areas N&W and eventually down to the coast.    




There is some rumblings in the modeling regarding the AO and or NAO becoming more favorable.  When of IF that happens, AND the snow pack in Canada builds, the pattern will shift such that the ability for the energy to phase early and slip to our west will begin to shift further east increasing the chances for snow.  Time will tell.

My gut is telling me that the pattern just isn't quite ready for snow yet, esp the Pac side of things. That said we do still have to watch how the blocking in the N Atlantic evolves in the modeling. If in the right place and the energy comes in at the right time there is def wintry possibilities still on the table.

Still way too much time and too many model runs to get excited, or write anything off just yet.