Wednesday, 13 June 2012

Summer, Fall and Winter Update

First I will start with the summer... 

In terms of the trough timing I believe that a trough will stick around the eastern part of the country from the 23rd or 24th to the last day or two of june. The models have been trending stronger with the trough and have it for a longer period of time. The trend is very clear if you take a look at the last few runs of the GFS ensembles. This trough will be accompanied by blocking up towards greenland keeping the trough in the east for a sustained period. The trough will lift out by the beginning of july with more ridging in the east. We are seeing a trend of more blocking and more troughs producing cold shots for the east. This is being caused by the el nino coming on which is already bringing some major cooling to many parts of the U.S such as the major cold shot in june and the one I believe is coming the last week of june. This type of cold would not have been seen in the la nina like pattern we saw during the winter. The reason for more cold shots is due to the plummeting of the SOI. In this type of pattern the SOI is the main driver of the type of weather we will see a week down the line. When the SOI values go down we see a cold pattern in the east overall. Now because we are in an El Nino pattern we are seeing more dips then rises in the SOI which is what will be causing the slightly cooler then normal summer in the east. Beyond this point as we get into july i believe that as the MJO heads into a weak phase three (a warm phase) and then into the origin which is very warm in july. This will happen after phase 2 (which is cold for the end of june). This MJO pattern going into the origin will be much similar to last year where we saw that which caused a july heat wave. This year I believe that we will see some pretty strong heat for about 5-10 days in mid july as the SOI values level off but nothing like last year. But don't worry after that the SOI values will continue to plummet again because that is the physical realities of the pattern that we are in which has the cool that will outweigh the warmth overall. I think after mid july we will see the cooling really take charge, although we are already seeing it now and will the last week of june. 

Winter and Fall thoughts...

In terms of winter not much has changed with my thoughts but I still believe that the PDO will flip to warm which is the main driver we should be looking at if we wan't cold and snow in the east next winter. If you look at the difference in temps between 1951-2/ 1972-3 and 1976-7,1957-8,2009-10 and 2002-03 it is very clear that the temporary positive spike in the pdo is making the huge difference. I believe that next winter will be cold for us in the great lakes with near average snowfall because the storm track will probably be pushed to the south in an el nino pattern. The big mistakes many are making is that they are looking at analogs with a cold pdo and not narrowing it down to the right ones. So someone might include 1951-2, 1972-3 and some warm PDO spike years when it doesn't make sense to do so. You either pick one or the other. I think if the PDO doesn't flip we will have a similar pattern to 1951-2 where it is warmer than normal with more moisture available. I think it starts early with plenty of lake effect snow. November i believe will be colder then normal as the cool core shifts east but the starts of the fall will average near normal to slightly above normal.  I think august is slightly cooler then normal and is also a cooler month (departure wise) then september which i always believed would be slightly above normal.  I am a little uncertain with regards to the specifics of the month of october although i believe we will undergo changes that month will the cool core beginning to shift east from near the west coast to the central U.S giving more cool shot opportunities from the north-west. I think november is when the cold will make its presence in the east for good and it will be a cold month overall. Im not exactly sure about the specifics regarding october and the core of cool shift that should occur.

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