Calculating pressure trend

Is there an accepted or defined standard for pressure trends?

I found the following on a website and wonder if this is just somebodies opinion or if it's documented somewhere legit?

Pressure Trend
shows the direction of change (higher, lower, steady) of the barometric pressure over the last three hours.

• "Rising Rapidly" is indicated if the pressure increases > 2 mb (0.06")
• "Rising Slowly" is indicated if the pressure increases >1 mb but < 2 mb (> 0.02" but < 0.06")
• "Steady" is indicated if the pressure changes < 1 mb (< 0.02")
• "Falling Slowly" is indicated if the pressure falls > 1 mb but < 2 mb (> 0.02" but < 0.06")
• "Falling Rapidly" is indicated when the pressure decreases > 2 mb (>0.06")
 
To answer your question in a nutshell...yes, there are specific guidelines that assign values to different pressure characteristics. The following are official National Weather Service guidlines as defined by the weather glossary:

Pressure Falling Rapidly
A decrease in station pressure at a rate of 0.06 inch of mercury or more per hour which totals 0.02 inch or more.

Pressure Rising Rapidly
An increase in station pressure at a rate of 0.06 inch of mercury or more per hour which totals 0.02 inch or more.

Pressure Unsteady
A pressure that fluctuates by 0.03 inch of mercury or more from the mean pressure during the period of measurement.

Hope this helps....
 
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