Weak Short-Wave Ridges And Troughs

From the afternoon NWS FD by Tucson: MAIN INFLECTION OF RIDGE AXIS PHASES THROUGH TODAY BUT RELATIVE  HEIGHT AND THICKNESS VALUES REMAIN HIGH AS A LARGER SCALE RIDGE FROM  THE EASTERN PACIFIC THROUGH CENTRAL MEXICO REMAINS IN CONTROL

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My attempt at translation (see the 500 mb NAM analysis top and the 12 hour forecast valid at 5 pm MST this afternoon - 10 March 2011): The weak southern portion of a ridge that extends northward into Canada was overhead this morning and will move slowly eastward today. There is a persistent 500 mb high located from the eastern Pacific into central Mexico (actually, I don't see this feature at all in the NAM or GFS forecasts, and it appears that the Gulf of Alaska cyclone and short-wave troughs along the northwest coast are the dominant features impacting western North America next few days - regardless, not much to write about down here).