As noted in the about page, I regularly check our sensors to be sure they are within specifications. Over the last couple weeks I have been conducting tests.
Temperature was right on. That’s typical, as our sensor is pretty bulletproof. I have a platinum RTD digital thermometer that’s accurate to within 0.1° F (best to check on a cloudy, windy night to eliminate radiation as a factor). I also have a laboratory-grade aspirated psychrometer with a dry bulb thermometer that’s extremely accurate. It’s analog, so the biggest challenge is reading between the lines. But my tests show the station’s thermal sensor is within 0.5° during the day which is quite good. There’s also a backup sensor on site as well. At night or on cloudy/rainy days, the two sensors are normally within 0.2° F. During sunny days, height (7 ft vs 21 ft) and shielding differences (active vs passive ventilation) can frequently lead to 1° differences in either direction. 2-3° differences are not out of the question when it’s particularly calm and sunny.
Continue reading “Instrument Calibrations”
Earlier this week I removed the cloud icons that formed the main navigation links throughout the site. This design methodology had passed its shelf life. It also limited the font size of the embedded text. By deploying more generic buttons I was able to change its font type & size. This should make navigation clearer & easier to use.
In the weather history section, you can now click on each of the 24 hour graphs at the top for a much larger, more detailed version of the image. These images are not straight duplicates of the data in the smaller graphs and contain some custom “enhancements”. For instance, the detailed dew point and humidity graphs contain corrected & smoothed values (rolling 5 minute averages to prevent readings from jumping around too much when the air is unstable). The software that connects the weather station to the website cannot correct for sensor errors in real time. I do that immediately after the reading is taken. Then I send the corrected values to the site (current conditions, history tables). Unfortunately the smaller graphs are generated before I can access them. Note that the larger dew point and humidity graphs are still “initializing” which means that some of the data from yesterday is missing. This will correct itself by about 8 PM Saturday evening.
I also fixed a small bug whereby if you had selected metric units in the page settings of the City page (home page) AND you also selected unrounded temperatures you would only see rounded temperatures.
Usually I wait until May 1st, but the upcoming 7-day forecast shows temperatures almost entirely above freezing with daily highs in the 40s & 50s. Some rain is possible next week. This is not what I would describe as “wintry” by U.P. standards. Since the site only has two modes, I think it’s time for “summer” mode.
This means that wind chill will no longer display in the current conditions on the City page (home page). Rain measurement will take its place to the right of temperature. However, until April 30th, you can monitor hourly wind chill via the daily table on the Weather History page.
Keep in mind that for wind chill to be calculated the temperature must be under 46° and the average wind speed must be at least 3 mph. Otherwise, the wind chill is the same as the ambient temperature. In actuality, wind chill remains very close to (if not identical to) the air temperature until the latter drops into the 20s and/or there are very strong winds.
If we get another cold spell this spring, I will return the site to winter mode temporarily. Let’s hope that’s not necessary!
P.S. If it snows in the next 7 days, it’s officially my fault.
UPDATE 5/9/2020: The website is temporarily back in winter mode due to the recent snowfall and cold temperatures. I anticipate by Tuesday the 12th I can return it to summer mode for good (knock wood).
The National Weather Service Marquette has experienced a radar transmitter failure. See updates below.
UPDATE 2/16/20 10:00 AM: Radar has been returned to service.
UPDATE 2/16/20 7:00 AM: Radar transmitter out of service again. Technician will work on it this morning.
UPDATE 2/13/20 1:20 PM: Radar has been returned to service.
UPDATE 2/12/20 2:40 PM: Parts are on order. Return to service expected by 4 PM tomorrow.
UPDATE 2/12/20 8:00 AM: Radar transmitter out of service again.
UPDATE 2/10/20 6:30 PM: Radar has been returned to service.
UPDATE 2/10/20 4:50 PM: Radar transmitter out of service again.
UPDATE 2/9/20 12:30 PM: Radar has been returned to service.
I normally don’t allow “Winter Weather Advisories” (WWA) to post on the City page (home page), because too often those end with unremarkable snow totals here. Also, people tune out after a certain point if they are constantly barraged with alerts, which can happen during the winter here. When you see an alert posted on our main page, you can generally place confidence in its importance and relevance to the city. Note that the detailed forecast will always specify accumulating precipitation within the next couple days regardless of alert status.
When I saw the Winter Weather Advisory hoisted on Friday (1/17/20), I decided to post it. I could see that just the front-end of the incoming storm was forecast to deliver 4-7″ in about 12 hours. I could also see that conditions were right for a decent amount of lake effect over the following 24 hours. The $64,000 question, as always, was “how much?”
Continue reading “Revising Alert Policy”