- Jul 11, 2019 at 9:14 pm #3601562ArthurBPL Member
I have a Suunto Ambit 3. First question. If I understand it correctly and this seems to be the pattern, the sea level barometric pressure on the watch is compensated by the gps altitude and will be steady as the altitude in hiking changes as long as the weather does not change. Correct? Second question. Therefore, it should be a good weather indicator of approaching storms if the pressure reading drops. Third question. Does this barometric prediction method even work in the typical pop up afternoon thunderstorms so common in the mountain west? It would seem to work well in a lot of the country where fronts move thru, but that less common in the mountains where pop ups are the rule there. Thoughts?Jul 12, 2019 at 4:00 pm #3601635Todd TBPL Member
@texasbbLocale: Pacific Northwest
The watch has a pressure sensor that has to be calibrated. My Suunto Core lets you do that by either setting the known (adjusted-to-sea-level) barometric pressure or the known elevation. I’ve found setting the baro a much better way to go.
I don’t know if the Ambit has the same “auto” setting as my Core, but if so I highly recommend using it. Calibrate while you’ve got access to a local weather report, then let the auto do it’s thing. It watches the rate of change in the pressure to intuit whether you’re moving or not, and adjusts either the baro setting or the elevation setting in response.
If you don’t have that auto feature, you have to just recalibrate as needed. The smart money is on (a) not going nuts recalibrating at every pass or lake (i.e., let the small weather changes average out) and (b) not expecting accuracy to more than a couple hundred feet.Jul 13, 2019 at 9:37 pm #3601748Bruce TolleyBPL Member
@btolleyLocale: San Francisco Bay Area
The manual is on the Suunto website,
From the Ambit3 manual:
“The weather trend indicator is comprised of two lines forming an arrow. Each line represents a 3-hour period. A change in barometric pressure greater than 2 hPa (0.59 inHg) over three hours triggers a change the direction of the arrow.”
You also have a storm warning:
“Storm alarm A significant drop in barometric pressure typically means a storm is coming and you should take cover. When the storm alarm is active, Suunto Ambit3 Peak sounds an alarm and flashes a storm symbol when the pressure drops 4 hPa (0.12 inHg) or more during a 3-hour period.”
I am no weather expert but I would posit that even a very local storm front causes a drop in barometric pressure. I occasionally use the weather indicator on my Suunto Vector but I find that the Mike Clelland LATS method works just as well for backpacking and does not require the manual calibration the Vector requires. LATS = look at the sky.
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