Teleconnections--WPO/EPO/AO/NAO/PNA

toople wrote:

amugs wrote:That snowmap is needed not 8 days out but 8 hours out like we had in 2013-14, 2014-15 with our storms.  Like this weekend, went for a SECS in the HV to a driving rainstorm.
Learning more and more the WPO & EPO is important for our winters to be winter.
This next storm has WNS maps showing a massive cutter to Buffalo, quite possible in this crap pattern to a great snowstorm to flip things around. Possible yes, but likely not placing any money on that bet until 12 hours out!! Sorry but the trends this winter have been bad overall as we get closer to game time.

Hi Amugs.  I know the EPO is very important for our winter.  I know we need negative EPO.  I’m curious; does WPO effect our weather too?  I couldn’t understand what WPO is for.

WPO= Western Pacific Oscillation
EPO= Eastern Pacific Oscillation
AO= Arctic Oscillation
NAO= North Atlantic Oscillation
PNA= Pacific North American Oscillation

WPO affects the weather more indirectly I suppose you could say as what is happening in this region affects what happens down stream.  Below is a representation of the general regions we are talking about when we speak about the WPO, EPO, AO, NAO and the PNA.  We refer to these acronyms as the "teleconnections".  We often speak about them individually in either a positive or negative phase.  See map below for geographic location of the teleconnection.  When we refer to these in a +/- state what we really are describing is whether these geographic locations at the 500mb level(aka 18,000feet above sea level) have either a ridge or a trough centered there.  Using the EPO region in an example when this teleconnection is in a pos state there is a trough there.  When it is in the neg state there is a ridge there.  The stronger the +/- tells us the strength of the trough/ridge in the EPO region, or any of the regions for that matter.   For the most part the ridge and trough configuration at this level of the atmosphere(500mb) tells us how the various jet stream behaves(ie: arctic/polar/pacific/sub tropical jet).  The jet streams configuration dictates where the air masses are derived from for a give location.  





Here is the current state of the EPO region.  It is and has been positive.  Keep in mind this is only one of many teleconnection in an unfavorable state right now, but gives you an idea of why a NEG EPO is typically important to have sustained cold in the eastern half of the CONUS.  As you can see the trough in the EPO region(+EPO) promotes this sort of jet configuration.  This combined with a +AO, and +NAO locks up the artcic air masses in the arctic regions and floods the northern half of North America with Pacific air.  The result is the anomalously warm temperatures as seen by the third image covering pretty much the entire NA continent.  The exception is in the NE wherethere is only slight colder than normal due to a cold frontal passage following the system that is going to bring us the rain today.    





HOWEVER, IF the EPO was negative and we had a ridge in this location the arctic jet typically looks like this, which you could eaily see the difference in hwre the air mass would be derived from in the east:





So back to the WPO depending on how strong a ridge or trough may be in that region ultimately affects the weather down stream over North America, but remember its the sum of all the moving parts that gives us the final answer.  So in addition to the influence on the weather pattern and jet stream configuration these 5 teleconnections have, so does the El Nino La nina status, so does the MJO status, so does the QBO status, so does the AMO status the PDO status, so does the stratospheric vortex status, AND the solar/space weather status.  Every single one of these things are intimately intertwined in such a way that no one on this planet has figured out in its entirety.  Every time we think we have it nailed down we get humbled by the true complexity yet beauty of it.  But hey thats how you learn.  I hope I clarified at least a little for you but I'm sure i've sparked many more questions as well.  Cheers