Pacific Pattern Taking On A Familiar Form

Before I get into the meat and bones of the blog, I have to mention that the verification scores on the global models as of late have been dreadful. The EURO is still scoring best, but not as high as it usually does. I'm not sure exactly why this is the case but the SSW (Sudden Stratospheric Warming) that recently took place over the last month to five weeks or so could be a reason.

For those who remember upper level patterns well, you can recall that this past winter seemed to always feature a large trough over Alaska with a constant upper-level low stalling & spinning in the PAC. NW that would disrupt the flow for the rest of the U.S. It was not until the SSW around mid-January that the 500 mb pattern "relaxed" a bit through most of February and that was when we saw most of our colder than normal and snowier than normal weather conditions along the northeastern U.S.

I can not help but notice that the current 500 mb pattern is heading in a direction similar to what the 2012-2013 winter featured...

Here is 12z EURO at 72 hours:

                              

Trough over Alaska and PAC NW with a temporary one in the eastern U.S. behind a cold front (I will get to the developing -NAO as well later on).

12z EURO @ 120 hours:



Much of the same (besides the -NAO).

12z EURO @ 216 hours:



Again...much of the same.

Here is a zoomed in look at the U.S. from 12z EURO @ 168 hours:



It will be interesting to see how the ENSO and PDO look 4-6 weeks from now. If this pattern persists, it would become apparent we are on our way to another negative PDO winter (not all that surprising since these things come in cycles). The ENSO has been interesting in the fact that it has looked pretty "Nino-ish" to me for much of the summer, which is why I think the hurricane season has been relatively quiet. It still remains in question, at least for me, whether or not this warming trend continues. It is difficult forecasting the ENSO far in advance which is why it is best to focus more on factual data.

Meanwhile, the NAO will be taking an impressive tumble downward, but the lack of Polar Vortex' given the time of year, plus the -PNA (zonal flow) in the west, should keep our temps around average still as we finish off the month of September.

Projected NAO from the GFS...




Have a good day,

Francesco Paparatto



Notes:

--2013-2014 Winter Outlook to be released Thanksgiving Day--

--All images of this blog courtesy of WeatherBell Analytics--

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