Strong winter correlation between EPO and Northeast

[Alpha5]

Surprised me....

Most people think of the PNA as having a strong relationship with northeastern pressure patterns, but it appears that the EPO wages, whether directly or indirectly, much more power during DJF.

Heres the surface temp correlation with the EPO and PNA. Notice how much stronger the correlation is for the northeastern US, while the PNA remains more variable, exerting only a weak influence over the GOM.

vs

H5, again notice the strong negative correlation over the NE with the EPO.

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[QVectorman]

http://www.crh.noaa.gov/dtx/winter_2002-03_outlook_review.php#eponao

Second paragraph in...they talk about the EPO feeding the NAO over the East Coast.

"While researching the NAO and EPO in the previous winters in the study, an interesting item was noted that tended to be more relevant in the El Niño winters. It appears that the EPO was as much (and sometimes more) of a determining factor to the overall temperature trend of the winter than the NAO. In some El Niño winters, it was noted that if the winter was dominated by a negative EPO, even when accompanied by a predominantly neutral to occasionally positive NAO, temperatures over Southeast Lower Michigan were generally normal to below while snowfall was normal to above. Logically then, the coldest PERIODS of any of the winters in the study were when BOTH the EPO and NAO were in a negative phase. Therefore, the negative EPO circulation helped set up and "feed" the Arctic air into the circulation of the negative NAO by amplifying a ridge along/near the West Coasts of the U.S. and Canada. Subsequently, the building of ridge along the West Coast encouraged the troughing and cold air delivery over the eastern half of the country. "

[Alpha5]

http://www.crh.noaa....view.php#eponao

Second paragraph in...they talk about the EPO feeding the NAO over the East Coast.

"While researching the NAO and EPO in the previous winters in the study, an interesting item was noted that tended to be more relevant in the El Niño winters. It appears that the EPO was as much (and sometimes more) of a determining factor to the overall temperature trend of the winter than the NAO. In some El Niño winters, it was noted that if the winter was dominated by a negative EPO, even when accompanied by a predominantly neutral to occasionally positive NAO, temperatures over Southeast Lower Michigan were generally normal to below while snowfall was normal to above. Logically then, the coldest PERIODS of any of the winters in the study were when BOTH the EPO and NAO were in a negative phase. Therefore, the negative EPO circulation helped set up and "feed" the Arctic air into the circulation of the negative NAO by amplifying a ridge along/near the West Coasts of the U.S. and Canada. Subsequently, the building of ridge along the West Coast encouraged the troughing and cold air delivery over the eastern half of the country. "

Good read. I've been doing a little research and it seems like the EPO does have a lot of control over the general flow over NA because it completes controls the strength of and effect mild PAC air has on the US. If you're stuck with a strong -EPO that promotes zonal flow and funnels in a strong PAC jet into the US, you're not likely to get a PNA spike or a digging trough in the east. On the other hand, if you can get a high up there, or even a low that phases the two streams together, anything to stop the zonal flow, you can slow things down enough to allow some nice troughs work their way in.

Now, the thing I've noticed looking at the KU books is that there really is no pattern with regards to the EPO. There have been KU's with a strong high over the GOA or a strong low. Again, a high would be ideal, but as long as the low is not accompanied by a High over the region north of Hawaii, things can go ok.

Been trying to dig up some more stuff, but there's really not that much EPO data online, and much of it is the EP/NP index, which has nothing to do with the EPO.