a new electronic gizmo called the Brunton
Sherpa. Don't think that because this device is named "Sherpa"
that this device is limited to high altitude hikers (Sherpas are
the Nepalese natives who serve as the backbone of Himalayan expeditions).
The Brunton Sherpa is well suited for any type of amateur weather
of the best things about the Brunton Sherpa is that it displays
an easy to read sixteen hour history of the barometric pressure
in a column graph so it is easy to see the current pressure and
determine if the pressure is rising or falling.
image tells us quite a bit about what kind of weather we can expect.
First, let's look at the historical graph. The historical graph
is a column graph and we can see that there are five entries along
the X axis. The five entries along the X axis represent measurements
taken over the course of 16 hours. The graph is read left (oldest)
to right (newest) measurement. The graphs on the X axis represent
the hours 16, 8, 4, 2, and 0.
we can see that between 16 and eight hours ago we saw a rise in
pressure. After the rise in pressure seen over eight hours ago
the pressure has held steady. The longer the pressure has held
steady, the longer we can expect the existing weather to remain
the same. On the flip side, if we see a rapid rise or fall of
pressure we can say that the current weather state will probably
not be around that long.
is this useful? If I arrive at the trailhead campground the night
before under clear skies and pressure slowly drops through the
night and continues on that trend in the early morning, I would
expect the weather to change to rain and I would also expect the
rain to hang around for a good part of the day. Not a good day
to take off the top and doors or forget the rain gear.
If I arrived at the trail campground during the evening in the
rain and the pressure remained the same all night long I would
expect the rain to hang around for quite a while. Again, not a
good day to leave the top and doors at home.
If the pressure is steady and remains the same and the weather
was clear when I arrived at the trail the night before the ride
I would expect good weather during the ride and I wouldn't bother
with the rain gear.
current conditions (when the picture was taken) was sunny without
a cloud in the sky. The pressure is holding steady over the last
eight hours and it rose between 16 and 8 hours ago, so I would
expect the same sunny skies overhead for the remainder of the
one thing to keep in mind is that changes in altitude will affect
the readings of a barometer, so if you're traveling from Ocracoke,
NC at sea level to Tellico, in the mountains of Western North
Carolina, you will encounter the rise in elevation that will affect
pressure and therefore possibly give you a false reading. One
way to overcome this is to clear the historical graph when you
arrive at the campsite or trail head, or just remember the time
that you arrived so you can discount any portion of the historical
graph that was recorded during a rapid ride of elevation.
the top and the doors on!
a palce to store the top and the doors.
like it's going to clear up.
your travels do not take you through a rapid rise in elevation
the historical graph should still be valid. Keep in mind, though,
that if your travels take you toward an approaching weather system
you will see a faster rise in pressure than if you are staying
in the same place and the weather system is slowly advancing toward
Brunton Sherpa can do quite a bit more than just display a historical
graph and current barometric pressure, but they are beyond the
scope of this article.