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--

--Come register at the NJ Strong Weather Forum--

http://www.njstrongweatherforum.com/

El Nino-Like Conditions Hindering Hurricane Development, Atlantic Not Helping

We are half way through the 2013 Atlantic Hurricane season and there has still not been a hurricane.

What gives!?

One thing I do find interesting is subsurface temps. in the Pacific since mid to late May have been rising. 

The ONI value for June, July, and August is not in yet, but I'm fairly certain it will show a positive (warming) trend in the 3.4-Nino region since real-time data continues to show gradual warmth over that area in the last month. For May, June, and July...the ONI was at -0.2 which is indicative of ENSO-neutral. In fact, "La Nada" has been in effect dating back to March of 2012. Therefore, the ENSO has not had any affect on our weather pattern for the last year and a half! 

Check out the two 500mb anomaly images of the Pacific Ocean from the 12z GFS below. The first one is valid for September 6th and the second one is valid for September 11th. 

                           

Both of these images show positive height anomalies continuing in the Pacific for at least the 1st half of September. There is even constant ridging being shown in the Pacific Northwest of the U.S. (upper right corner of those maps). What this is telling me is the Pacific is undergoing a transition of breaking out of the year and a half long La Nada and trying to emerge into an El Nino state. I can not say with guarantee we are heading toward an El Nino until official reports and observations from the Nino regions prove otherwise. But latest indices are enticing, to say the least. One thing for sure is La Nada will persist through the upcoming fall season. 

How about the Atlantic Ocean? 

The NAO has been positive for much of the summer. Ridging has been concentrated in the central Atlantic, while the northeastern Atlantic (near Greenland) has been under the influence of trough's. Between the ridging in the Pac. NW and the central Atlantic, the eastern CONUS has enjoyed an average Meteorological Summer with episodes of troughs getting into the region. 

This has allowed the SAL (Saharan Air Layer) to remain intact over the Atlantic for much of the season. This GIF taken from WeatherBell will show you what I mean...

The colors represent the dust coming out of western Africa. A new wave of SAL is set to come off of Africa by the weekend. 

Between the combination of westerly winds in the eastern U.S. caused by the constant ridging in the west, the SAL in the Atlantic, and the lack of blocking in Greenland...the hurricane season has not gone as expected thus far in 2013 (even with an MJO favored for tropical development). Additionally, the recent trend of warming in the Pacific has caused the upper level wind flow in the Atlantic to remain unfavorable. 

Speaking of MJO, the EURO wants to take it into the COD (circle of death) by next week:

The only silver lining I see for those who are looking for tropical development is some long range models are trying to push a ridge into the eastern U.S. which would force the ridging over the central Atlantic to propagate east-northeastward. Whether this comes to fruition or not remains to be seen. Also, it only takes one storm to really make a hurricane season one to remember. There is still the 2nd half of September (I'm forecasting 1st half of September to remain quiet) and all of October. We'll see what happens. 

Take care,

-Frank 

Notes:

1. Register to the NJ Strong Wx Forum. Now up to 183 registered members with lots of great minds to share valuable information

http://www.njstrongweatherforum.com/

2. 2013-2014 Winter Outlook to be released Thanksgiving Day.