Feb 1, 2007 at 3:06 am #1221577
I am looking for a watch that gives an alert when the barometric pressure drops rapidly. While many monitor barometric trends, I would likely overlook a sudden drop if it did not alert me. Is anyone aware of a watch that incorporates this function?
Thanks!Feb 1, 2007 at 12:34 pm #1376728
Victor KarpenkoBPL Member
@viktorLocale: Northern California
Tissot has a watch that claims to have this ability. It is the T-Touch. I have used the watch and it seems to be able to forecast the weather.
From their user manual:
"The T-Touch watch measures these pressure variations and
indicates the meteorological trend for the coming 24 hours."
Their website is:Feb 1, 2007 at 12:57 pm #1376734
@bjamesdLocale: South Coast of BC
A bunch of the Suuntos do it. Go to Suunto.com, invoke their comparator tool, and it will list all the watches that have barometer alarms.
BrianFeb 1, 2007 at 1:24 pm #1376741
Joe KusterBPL Member
I have the Suunto Observer and it does a very good job at tracking barometric pressure. I believe (I haven't memorized all the features) it lacks the baro alarm but others in the suunto line offer it. Keep in mind you must recalibrate any altimeter / baro watch regularly to keep the functions working reliably and you must be educated on how they function to get much out of them. Take a look at the X6 – I think when I was shopping for my observer it had that feature.Feb 1, 2007 at 10:42 pm #1376814
None of these watches have the barometric rate-of-change (ROC) alarm you are looking for. The various Suuntos and the Casio I use, all have altitude target alarms, not baro rate-of-change alarms.
And there is a very good reason they don't..
These wrist barometers have the info they need to implement such an alarm, but the watch does not know weather a reduction in baro pressure is indicative of an incoming low-pressure storm system, an increase in pressure altitude, or both!
The change in barometric pressure indicative of an approaching storm system is VERY minor compared with the altitude changes a typical mountain hiker would experience.
For example, referring to my desk reference (The Mountaineering Handbook by Connally), we see the following warnings..
1. 40-60 feet "apparent" (as read on a stationary altimeter) altitude gain over 3 hours – mountaineer should watch for lowering clouds.
2. 60-80 feet in 3 hours – consider bailing on summit bid
3. More than 80 feet in 3 hours – head for the cars!
4. 1000 feet over night gain at base camp – middle of a SERIOUS storm.
If the barometer/altimeter watch was not staionary, and you were hiking up and down with it, you would probably experience a pressure altitude change of more than 80 feet (about 2.963mb) in 3 hours, unless you hike slow as a snail, or are in one of those 'fly over' states which is flat as a frypan. Remember the rule of thumb that 1mb of mercury is equivalent to an altitude change of 27 feet (true at sea level). Your watch does not know "why" the pressure is changing.. And if the weather was getting worse, but you were hiking downhill at a certain rate, the alarm wouldn't warn you anyway!
What you are looking for CAN be found in marine units. All marine units operate at a fairly constant geopotential altitude (0 feet Mean Sea Level plus or minus waves, tidal surge, etc, in the oceans) therefore all barometric changes they sense are due to weather change, and such an alarm would have more validity.
Here is just such a marine unit, costs about $100 and uses 2 AAA batteries:
"Alarm feature to signal abrupt changes in pressure"
I have avoided discussing another wrinkle in this subject, which really throws wrist altimeters for a loop; non ISA standard pressure lapse rates and non ISA temperature. Subject for another post, but for now… here's a quick test for all you altimeter owners; calibrate so your unit shows the true altitude, and toss your device in the freezer for about 10 minuntes.. did the indicated altitude change? Is this good or bad, and why?? Anyone care??Feb 2, 2007 at 3:28 pm #1376924
I appreciate the help and am amazed at the expertise/experience that often comes through these posts. I understand the altitude/barometric issue now and will "recalibrate" my expectations to only consider it for overnite stationary utility in camp.
The Tissot does look interestion on the web – expensive but interesting. Any idea of the weight?
MikeFeb 5, 2007 at 7:26 am #1377175
Joe KusterBPL Member
Your right on most of your comments in your post, but some Suuntos (like the observer I have) have a barometric or altitude pressure lock. When you set it to be an altimiter it locks in the barometric pressure readings assuming they don't change or vice versa. This allows it to be used as a fairly accurate altimeter, or when stationary an accurate barometer. Temp compensation in baro is a legit issue, but for any real weather readings you always have to remove the watch for it's thermometer to work and the alti lock will prevent temp changes from causing your altitude to drift.
To my knowledge no pressure based barometer / alti system will accurately predict weather while altitude is changing regardless of what you do. Perhaps a model that uses GPS altitudes in conjunction with a baro could, but I don't believe those currently exist in a watch.Feb 9, 2007 at 2:34 pm #1377845
An update on the Tissot T-Touch watch above: This watch indeed appears elegant and does have the alarm but it turns out to weight 350-400 grams and cost around $450.
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