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Basic Wind Speed
The Basic wind speed is used to create loads for shear wall design calculations, and deflection calculations when used to distribute forces to shear walls. For the continental USA, they are to be taken from maps in Figures 26.5-1 A-D for each Risk Category. Figures 26.5-2 A-D are maps for Hawaii. This is a 3-second gust wind speed for exposure C at 10 m above the ground, corresponding to 15% chance of exceedance in 50 years.
MRI (serviceability) wind speed
The MRI (serviceability) wind speed is used to create loads for deflection calculations used for story drift, as per ASCE 7 CC.2.2 . They are to be taken from maps in Figures CC1 to CC4, corresponding to mean recurrence intervals (MRI) of 10, 25, 50, and 100 years, respectively. It is up to yoir judgment as to which of these to choose.
Change from ASCE 7-05 to ASCE 7-10
In conjunction with the addition of a 0.6 ASD wind load combination factor, the wind speed maps that were provided with ASCE 7-10 in general increased wind speeds by the square root of 1/ 0.6 when compared with ASCE 7-05; however it the maps also incorporated the importance factor and also may have changed due to new meteorological conditions.
Wind loads from project files made with version 9.x and before should not be used with version 10 and later, as loads made from the lower wind speeds will be factored down by 0.6, creating a very non-conservative error.