Tuesday 1 January 2013

Long Range January Outlook


The MJO is headed into unfavourable phases 3,4 and 5 for the second week of january. This correlates well with the january thaw across the east advertised by the ECM and GFS model guidance. With the neutral enso state we should be watching the MJO, SOI values and stratosphere for guidance as other signals have less of an effect on the overall north american weather pattern.
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Temperature anomales from the GEFS:
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According to the GEFS, signs are pointing towards a more favourable MJO pattern for the last week of january and into the beginning of february. How fast the MJO wave propagates around the globe varies between the ECMWF and GFS. The euro is much slower with the MJO wave and continues to bank on an unfavourable pattern into the beginning of february. The GFS builds frigid air across central and western canada in week two and three of january. This allows the cold air to move east for week four with the SSW event coming up.
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The european weeklies are showing a much different solution with much warmer then normal temps in the east for weeks 2 through 4 in january and the cold air locking up in the west and prairies. This is enough to make you second guess yourself, especially because this is the best performing model. I am still not convinced that the cold won't deliver in the second half of january. Now let's all remember that the MJO has a large effect on the subtropical jet stream but does not drive the polar jet stream. This means that a southeast ridge will be favoured in the second half of january as well as a trough in the southwest. With the upcoming SSW event the PV will drop south into central and eastern canada which will shift the polar jet south and cause a -ao pattern. The stratosphere will be the major driver of our weather pattern across canada. Although the southeast and east coast may be near to above normal that does not mean that we are out of the woods in eastern canada. What I see setting up in the second and third week of january is a frigid pattern in the west and prairies and an active SE ridge causing the storm track to form along the BZ across the st lawrence river valley and eastern lakes. By the forth week of january and first week of february the PV should drop Southeastwards leading to a colder then normal pattern across the east. The PV is already on our side of the globe which means that the cold air is much more available then last year and is not likely to propagate into other parts of the globe. With the MJO heading into more favourable phases around the last ten days of january a much colder and snowier pattern looks increasingly likely, despite the european's frightening outlook.
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