10/20/20

LA NINA WINTER IS ASSURED FOR WINTER 2020-21 ~ BUT OF WHAT INTENSITY?

Latest data coming in on the La Nina developing over the Pacific for the upcoming winter continues to change - and intensify - with updates; especially with the American CFSv2. Latest data shows the differences in each individual model and within the CFSv2 itself. Researching ahead of my traditional Winter Outlook is bringing up some interesting trending features in the CFSv2.

First off; here's where we are as of early-mid October as far as La Nina (note the increase in below normal anomaly sea surface temps in blue - /SST/)

 

 
 
CFSv2 Modeling as of mid October
 
 

As you can see by the dashed ave line (above) on the Nina 3.4 SST forecast; the CFSv2 has gone full marks on the La Nina anomaly intensity by projecting a solid -2.2C or strong La Nina this winter. The CFSv2 Model sits in the outlying range for La Nina intensity this go-around and it does appear she's a bit aggressive at this time.

Meanwhile; other dynamic and statistical models have their own idea how strong the La Nina will be this winter (below).

 


The consolidation zero's in around -1.5C or Moderate La Nina


In my process of "analoging"; I try to align similar hemispheric and local patterns in previous similar ENSO years to match up with the present patterns. Sometimes, these similar patterns can go back several months and even years. And, these are not only meteorological patterns; various ocean cycles and solar cycles are researched and where possible, paralleled and also considered.  Of course this can lead to problems from the "get-go" when and if ENSO projection models are varying on what type of ENSO, strength and timing. Usually the type of ENSO isn't as much of an issue as its strength and timing (actually, really not unlike general weather forecasting).

Below are the CFSv2 latest ENSO SST La Nina forecast - November - and the winter. But remember; the model is projecting a strong la Nina through the winter and it's one of the strongest.


The temperature/precipitation winter forecasts (below) are very interesting from the CFSv2 and is beginning to reflect what I'm seeing in Long Range GFS/CFS. Very cold air storing up in Canada, milder conditions in the much of southern and central States and strong baroclinic zone across the northern tier of the US. And, of course, SE Lower Michigan is in that zone. Remember, the CFSv2 is just showing temperature and precipitation anomalies based on its ENSO outlook. Therefore at this junction; this particular model projection shows basically a normal to slightly above normal temperature winter accompanied by above normal precipitation.

There is a lot more current and Global Model information pouring in now along with my hybrid set of Winter Analogues.

Look for my Winter Outlook in November.

Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian