Some Changes To The US Pattern With West Pacific/MJO Worth Watching

Written by Mark Vogan on July 6, 2015 in Summer 2015, Tropical, United States of America with 0 Comments

As we head into the heart of July and indeed this summer season I can see some changes taking place. A cooler, wetter pattern beginning to show in the Southeast where it got pretty hot and dry last month. The big ridge up in the Pacific Northwest and even Southwest for that matter looks to be gradually breaking down as a more Rockies position appears likely. This position will allow higher dew point air to drift up from Mexico sparking showers and thunderstorms. Less extreme heat as a result.

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We also have to watch what’s going on in the western Pacific as the strong phase 7 of the MJO crosses the region and acts as an incubator for tropical formation. Speaking of the tropics, we’ve got two typhoons we’re currently watching. The first is taking a due west path into China and it could be a big deal to China. The 2nd typhoon, according to the latest models appears to recurve, staying east of Japan. Both suggest an initial ridge over the Northeast followed by a trough.

Check out just how strong this phase 7 is of the MJO.

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It does weaken within the next 10 days but I still urge you to keep an eye on the eastern Pacific towards mid-month and shortly after I would be watching the Caribbean, especially if we have a setup where there’s upper lows crossing the Southeast.

Here’s the first typhoon (Chan-hom) which slams China. This should support positive heights over the Eastern US but heights are supressed over the South and Southeast.

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Credit: AccuWeather Pro

Here’s the second typhoon (Nangka) and with a recurve track, this should respond to an eastern trough in the 6-10 day.

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Credit: AccuWeather Pro

Looks like there’s quite the ridge building up over the western High Plains day 5-10 and particularly day 10-15. Get ready for the commencement of the 2015 monsoon with this setup.

The 0-15 day EPS control 5-day mean 500mb height anomalies is similar to the GFS ensemble with SW trough/NE ridge day 0-5, big ridge building over E Rockies/W Plains with shallow NE trough but it doesn’t see the trough day 10-15. This makes me think the model doesn’t see the recurve with the second typhoon.