Real Wx Service 2011 Preliminary Hurricane Outlook

Hurricane season is just around the corner beginning in the month of May going thru the month of November. We are currently in the midst of a La Nina , this La Nina is fading or weakening but we expect the La Nina to last thru the summer.  A La Nina for hurricane season can cause more East Coast landfalls for Hurricanes. And we are anticipating that this year. However...those looking for a landfall in the Northern Mid Atlantic and points to the North will probably be disappointed. 
Lets look at a few things that will play an important role in this hurricane season.


ENSO..


As we have already stated we are currently in a La Nina and that is expected to remain during the summer . Majority of your enso models show this..though admittedly there are some that want to go into a warmer phase..

We feel that even if the ENSO were to go into the warmer phase as shown above by some models that the atmosphere will respond more slowly as there is always a lag time effect. For example..this latest winter was still acting more like an El Nino ..then La Nina (until Feb 2011) even though this was a La Nina winter. It is that lag time effect that is the reason for that happening. 


Pacific Decadal Oscillation

As you can see by the above image we are currently in a negative phase of the Pacific Decadal Oscillation. 

Atlantic MultiDecadal Oscillation

Since the mid 1990's we have been in a warm phase of the AMO. Warm Phase of the AMO has been found to increase Atlantic Hurricanes along with there intensity due to the ocean temperatures being warmer then normal. It acts as a fuel aiding development of the Tropical Cyclones.

So, what we have done for this preliminary outlook is we have gone back and looked at the El Nino winter years that had then transitioned to a La Nina for the summer. When we did this we came across the following years..

1 1963-64

 2. 1973-74

 3. 1987-88

 4. 1997-98

     5. 2009-2010

From there we have narrowed down the list above to only include those years that we had a Negative PDO and a Positive AMO. When we do this we come down to the years of 1964, 1998, 2010. So these would be the two analog years that we are using for the 2011-2012 hurricane season.

1964 Hurricane season we saw a total of 12 storms with 6 hurricanes

1998 Hurricane season we saw a total of 14 storms with 10 hurricanes

2010 Hurricane season we saw a total of 21 storms and 12 hurricanes

As you can see the three analog years that come into play with the teleconnections that we have present were indeed very active seasons with a decent amount of hurricanes. So, once again we are expecting a active season with a total of 15-18 Named storms of which 9 out of those named storms will be Hurricanes. This is calculated by taking the average of the three years above. 

Now when looking at those three years you will see that the threat for US Landfalls  was pretty decent in 2 out of the three years with 1964 offering 4 US Landfalls ..1998 offering 7 US landfalls . 2010 however, only offered one US Landfall. All three years brought storms up and near the east coast and some cases inland along the east coast which enhanced the heavy rainfall threats along the east coast. So we are basically expecting some US Landfalls and the primary areas for this to occur would be over the Southeast and the Gulf Of Mexico region. If we continue to see strong ridging over the Western Atlantic then these storms after landfall would be able to move thru the Southeast bringing there heavy rains into the Mid Atlantic & Northeast.

This is a preliminary outlook at this point and time and will be fine tuned in the month of April and we will continue to monitor all of the above and then issue the final forecast in the month of April 2011.