Hurricane season & Winter Season Research!

When we released the Winter Outlook for 2010-2011 ..we looked at something new for the winter forecast season and that was to see if there was a relation between and active hurricane season and a colder and snowier then normal winter season.

What we did is we took the top ten active hurricane seasons for “named storms” ..those years were as follows:

1995 -19 storms
1887 -19 storms
1969 -18 storms
2008 - 16 storms
2003 -16 storms
1936 -16 storms
2007 - 15 storms
2004 -15 storms
2001 -15 storms
2000- 15 storms

We could also add on to this the year 2010 as that season had 21 named storms.  Now looking at the list above since we have transitioned into a La Nina this hurricane season we have to determine what years were La Nina years and then we are going to look at the winter that followed those La Nina hurricane seasons. What this means is if the winter that followed the La Nina hurricane season was not a La Nina it will not be included.

The purpose of this is to determine if a active hurricane La Nina season is followed by a colder & snowier winter.

So looking at the list above the following were La Nina winters ..

1996, 1970, 2008, 2001, and we can add 2011.. Records of La Nina /El Nino do not go back as far as 1888 to make the determination of whether La Nina/El Nino so we will not include that year for not enough data..

So when we look at these winters that followed La Nina Hurricane seasons we look like the  following:

Now as you can see out of the 5 years that were left “4” out of the 5 were colder then normal across the east and NE and majority of the country.

Granted it is a small sample size but the theory is that an active La Nina hurricane season followed by a La Nina winter resulted in a colder then normal winter four out of five times.

Now out of those 5 years above only two of them had a – PDO and those were 2008 and 2011.

Now out of those two years only 2008 had a negative QBO  to go along with the –PDO..but as we see the results of 2008 were the one year that ended up above normal temperature wise. This may lead a person to then think that we should be looking towards a warmer then normal winter . However..the difference maker we believe comes down to the AO and NAO .

The above is the NAO & AO time series which if you look at 2008 you can clearly see we were dealing with a positive NAO and a positive AO. There after you can see that we have been dealing with predominantly negative NAO and negative AO ..Also refer to images from the last research post issued a couple days ago.

The research provides shows a couple things. First it shows that a La Nina winter following a La Nina hurricane season four out of five times ended up colder then normal. The second thing that it shows is that the most important equation of the winter forecast is the AO & NAO.

The end result equals active La Nina hurricane season followed by a La Nina winter with a –NAO &-AO four out of five times has resulted in a colder then normal winter which leads to more evidence towards a colder then normal winter forecast as was issued by Real Wx Service along with Lehigh Valley Weather Patrol!