How to find the local Sea Level Pressure

October 18, 2004 8:14 AM

WeatherFilter: How can i find my Sea Level Pressure of my area? [mi]

I just got a Suunto Vector watch, and it has a atmospheric barometer (and it can tell the altitude), anyway in order to set it up properly (and so the altitude doesn't change every time the pressure does, I need to find my Sea Level pressure. My goggle-fu had been weak on this.

posted by ShawnString to Science & Nature (2 answers total)

1. Go to http://adds.aviationweather.noaa.gov

2. Click on the METARs tab.

3. Type in the four-letter code for your nearest mid- to large-size airport. If you're familiar with the three-letter code (e.g. ORD, STL, PIT, LAX), stick a K in front.

4. Select the "Translated" option.

5. Look on the results page. If you're lucky, sea level pressure will be there in millibars. If not, you can get surface pressure in inches of mercury, and use the rule-of-thumb lapse rate of one additional inch of mercury for every thousand feet above sea level. Multiply 1"/1000' by your altitude, add to the reported value, and you're set. Of course, if you know your altitude already, it's probably easiest to just calibrate based on that.

Be advised that sea level pressure DOES change with the weather, so you will have to calibrate your altimeter occasionally. Pilots do it several times during every flight.
posted by tss at 8:31 AM on October 18, 2004

thanks...it was there...and stupidly enough, it was the default one....
posted by ShawnString at 8:54 AM on October 18, 2004