The weather station takes a round of measurements every minute. Each bar in each graph represents an hour, always beginning at minute 00 and ending at minute 59, so each bar is a summary of sixty observations. There is no summary bar for the current hour, since it has not yet reached its 59-th minute.
A guiding principle on the size of the page was that you could print all the (important) data on one page.
Top of RED bar -> Maximum (for hour) Bottom of RED bar -> Minimum (for hour) Bottom of BLUE bar -> Minimum (for period) The bottom blue bar may be further split into green-over-blue when it straddles the freezing mark. The green-blue boundary represents 32 degrees F. A rimed sensor can occur in the early hours of a juicy storm. The sensor can still indicate temperatures below freezing, though its response (inside a ball of ice) will be slowed. When temperatures rise above freezing, due to the heat of fusion of water, the temperature inside the rime mass will remain at "freezing" until the sensor melts free. The temperature will then appear to jump quickly. A broken sensor may indicate unusually cold (-30) or hot (+120) tempeatures. Back-up temperature sensors are available, which will be automatically selected if the program judges the primary sensor to be unreliable. Back-up readings will have a small "S" or "T" (for secondary or tertiary sensor) included with their current reading if they have been selected. About this sensor "Mid-mountain" temperature is measured near the top of the Manzanita lift. Elevation-wise this is about halfway up the hill. It should be about 2F (1C) warmer than the top temperature. "Base Area" temperature is measured at the bottom of the hill, at the South Lodge (near the parking lot). It should normally be about 4F (2C) warmer than the top temperature. This is mostly of interest when cold air drainage fills the bowl with cold air, while higher on the hill it can be much warmer.
Top of RED bar -> Maximum (for hour) Bottom of RED bar -> Minimum (for hour) Bottom of BLUE bar -> Minimum (for period) The humidity sensor is in the same enclosure as the temperature sensor. When rime ice encases the humidity sensor, it cannot sense what is going on outside. The humidity reported is that of the inside of a snowball: Near, but not quite, 100%. Wildly varying values might be a good indication of a broken sensor. Values stuck level at around 97% might indicate a rimed sensor, or a slightly drifted calibration exposed to fog (= 100%). The temperature being above or below freezing could provide a clue. About this sensor
Top of RED bar -> Maximum (for hour) Bottom of RED bar -> Average (for hour) Bottom of BLUE bar -> Zero The wind speed is measured in "free air" at the top of a tower on top of the mountain. You will probably experience much gentler winds if you are located elsewhere on the mountain or down amongst the trees. "Maximum" wind speed is measured over the span of one minute. Gusts can have 3 second bursts that go even higher, but we cannot capture those events. "Average" wind speed is the vector average of a number measurements (such as over the 48 hour period). The idea is to understand, on average, where a volume of air which passed by the sensor at the start of the time period has gotten by the end of the time period. An day of 25 MPH from the west, followed by a day 25 MPH from the east, would vector average to 0 MPH. After the two days, the air is back where it started, and achieved an average speed of zero! If the "average" wind speed looks too low, look to see if the wind direction has turned around during the time period. If this sensor is "broken" it will indicate a zero wind speed. Historically, the wind on top of the mountain rarely stops for more than a few minutes. In severe icing conditions the sensor may slow or even stop. When the storm eases or temperatures rise, the internal heater should restore it to operation. See the "Wind Direction" discussion for an quirk related to when winds come from the South. About this sensor
Top of entire bar -> North = 000 degree azimuth Span of RED bar -> Includes all observed directions Bottom of the bar -> North = 360 degree azimuth "Dir" directions are reported in 8-point compass (N, NE, E, SE, ...) so the graphical display spans a consistent width. Labels for directions like "NNE" would be too wide, so a 16-point compass could not be used. Top-to-bottom the graph shows North-East-South-West-North, with small horizontal lines to indicate the cardinal directions. A symptom of a broken sensor may be that it indicates a constant "N"orth direction. One little problem when winds come from the South: There's a rather large building not far away from the sensor in that direction. The building acts as a windbreak, slowing the apparent wind speed and shedding vortices which tend to make the wind appear to be coming from most any direction. Fortunately the wind doesn't blow a lot from the south. It can be detected by watching the 48 hour trend, looking for when the wind direction appears to be trending toward South. When it happens the band of azimuths covered by the wind direction will appear to jump around erratically. The band may also become much wider. About this sensor
Top of RED bar -> Maximum (for hour) Bottom of RED bar -> Minimum (for hour) Bottom of BLUE bar -> Minimum (for period) About this sensor
Top of RED bar -> Maximum (for hour) Bottom of RED bar -> Minimum (for hour) Bottom of BLUE bar -> Minimum (for period) Short-term variations are primarily due to temperature and wind effects over the ultrasonic sensing path. Long-term variations are primarily due to precipitation and settling of the snow pack under its own weight. - Snow which falls at temperatures below 20F is normally light, and will eventually settle significantly. - Snow which falls at temperatures above 25F tend to be denser (= heavier), and will settle faster but less than lighter snows. Absolutely no variation is an indication of a sensor which has lost power. (Sometimes someone turns-off more than just the lights at night!) The maximum measureable depth is 204" due to the height of the sensor above ground level (240.1") less the sensor's minimum range spec (36"). About this sensor
Top of RED bar -> Maximum (for hour) Bottom of RED bar -> Minimum (for hour) Bottom of BLUE bar -> Minimum (for period) Short-term variations are primarily due to temperature effects. These are especially observable in the Summer. Some attempt has been made to correct for this, but about 1/3 of the variation remains. When the temperature drops below +5F it appeared (Winter 2006) that the antifreeze failed, and there were really odd variations. About this sensor
Top of RED bar -> Total counts for the hour Bottom of RED bar -> Zero This data channel attempts to provide a relative indication of the lightning activity associated with nearby thunderstorms. The sensor counts the number of "static bursts" it hears on a simple radio. This data channel should allow us to track a storm's activity: As it becomes active, and as it fades away. With experience we may be able to refine what "nearby" means, but for now let's just hope it works! There probably will be some amount of background noise due to man-made sources. Touching the antenna sets it off, so operating lights and tools in the building may also excite it, as well as power line glitches. Don't get excited just because we're reporting some counts. About this sensor
Top of RED bar -> Maximum (for hour)
Bottom of RED bar -> Minimum (for hour)
Bottom of BLUE bar -> Zero
Spikes seen during night-time hours are usually due to the snow
grooming equipment passing by with their flashing lights.
"Twilight" - Sun's center is 6 degrees below the horizon.
- This is the definition of "civil twilight",
which is about the time it becomes too dark
to work or play outside.
"Sunrise" & "Sunset" - Sun's upper limb is on the horizon
"Moon Phase" - The sign indicates waxing (+) or waning (-).
- The number is the percent of a full moon.
e.g. +0% = new moon
+25% = waxing crescent
+100% = full moon
-75% = waning gibbous
- The number changes about 6.8% in 24 hours.
About this sensor
The power rail is what supplies power to the datalogger. It can be driven by either a plug-in power supply or a back-up battery. - When commercial power is available it is steady at about 13.0 Volts. - In the event of a power failure the batteries provide a lower voltage, which will decline as they become exhausted. - The minimum operational voltage for the datalogger (the data collecting part of this weather station) is 9.6 Volts.Common to all of the data section graphs:
This is done so that the 48 hourly bars are close enough together so they will print gracefully on a single page. Every six hours a wide bar is provided so that it may be labeled with the time (and usually a reading).
"!" indicates a where a maximum or minimum occurred if the value is not printed.
The number is the hour in 24-hour format:
0 -> Midnight
6 -> 6 AM
12 -> Noon
18 -> 6 PM
Other notes:
Views of various mountains as seen from the weather station site. These include Mt Jefferson, Three Fingered Jack, Black Butte, Cache Mountain, Mt Washington, North Sister, Middle & South Sister and Iron Mountain. The picture is changed every hour. The pictures are intentionally small (to minimize download time), low-contrast and grey (to provide texture, but not interfere with the page's readability). The "embossed" image option was used to highlight the remaining edge contrast.