Report

Space weather: solar flux 105, 9 below its 90-day average of 114. Maximum usable frequency 12 megahertz, measured by the Idaho Falls ionosonde via KC2G: long-distance paths open through 30 meters, 20 meters and up closed. Critical frequency 4.2 megahertz, so 80 meters is good for NVIS. K index 4, active. No significant flares. Data from NOAA.

The declining phase of the solar cycle often brings some of the cycle's strongest flares and geomagnetic storms, so VHF aurora openings on 6 and 2 meters are still very possible.

Sun and moon, Pacific Daylight Time: sunrise 7:08 AM, sunset 6:48 PM, day length 11 hours 40 minutes. Moonrise 12:27 AM at 58 degrees, east northeast; moonset 3:40 PM at 299 degrees, west northwest. Waning crescent, 32 percent lit. The Orionid meteor shower peaks Wednesday, October 21, a meteor scatter opportunity on 6 and 2 meters. Moonbounce: the moon peaks tomorrow at 9:02 AM, 71 degrees high and 3 percent closer than average, a good time to listen for EME signals on 2 meters and up.

After sunrise the D layer builds, and 160 and 80 meters go quiet on daytime paths within an hour or two.

Amateur satellite passes for the next four hours. No passes above 30 degrees in the next four hours. Frequencies and live status at amsat.org/status. Pass predictions at n2yo.com.

Satellite tip: image satellites are receive-only. An FM receiver and a phone app such as Robot 36 can decode their pictures; set the app to the satellite's mode, or let it detect the mode automatically.

DX activity, via the cluster network and hamqsl.com. None spotted by West Coast stations right now. No aurora or 6 meter E-skip.

Tropospheric ducting, from balloon soundings 17 hours ago: Newer data is not yet available, and conditions may have changed. over Oakland, a duct at 800 to 1100 feet, good for 33 centimeters and up. No matching ducts along the coast or toward Hawaii, so the enhancement is likely local. K6EEG's experimental tropo forecast, based on NOAA atmospheric model data, for the next 12 hours. Bay Area coast, peaking around 9 AM: ducting expected on 70 centimeters, 80 percent; a chance of ducting on 2 meters, 35 percent. Southern California coast, peaking around 12 AM: ducting expected on 70 centimeters, 95 percent; ducting likely on 2 meters, 70 percent. Pacific Northwest coast: ducting expected on 70 centimeters, 90 percent; a chance of ducting on 2 meters, 30 percent. Nothing toward Hawaii.

Tropo openings favor horizontal antennas. Calling frequencies, upper sideband: 144.2 and 432.1 megahertz.

Events. The California QSO Party, now under way, California stations in demand. IARU Region 1UHF/Microwaves Contest, today. VHF-UHF FT8 Activity Contest, on Wednesday.

Club and community announcements. The SF Amateur Radio Club meets on the third Friday of each month, 7 PM at the Randall Museum. Visit sfarc.org for more details.

Check into a local net this week. Regular net practice is what makes emergency nets work. Test your go-kit monthly, and rotate batteries and supplies.

Current weather conditions at San Francisco International Airport: Clear. Temperature 68 degrees Fahrenheit. Dew point 57 degrees Fahrenheit. Relative humidity 68 percent. Wind calm. Barometric pressure 29.92 inches of mercury, normal. Visibility 10 miles.

National Weather Service forecast. Tonight: Mostly clear, with a low around 61. West southwest wind around 5 miles per hour. Monday: Sunny. High near 80, with temperatures falling to around 74 in the afternoon. West wind 1 to 10 miles per hour. Monday Night: Mostly clear, with a low around 60. West southwest wind 2 to 9 miles per hour.

Tide predictions for today at the San Francisco Embarcadero gauge. Low tide at 12:34 AM, minus 0.1 feet. High tide at 8:16 AM, 4.7 feet. Low tide at 12:48 PM, 3.3 feet. High tide at 6:32 PM, 5.6 feet.

Ocean and bay conditions. No marine advisories in effect. From the San Francisco buoy, 18 nautical miles west of the Golden Gate: significant wave height 3 feet, slight seas, dominant period 15 seconds, from the south southwest. That's long-period ground swell. Wind at the buoy 8 knots from the west northwest. Ocean water temperature 61 degrees Fahrenheit. San Francisco Bay water temperature 67 degrees Fahrenheit. Golden Gate currents: maximum ebb 3.1 knots at 11:14 PM, then slack water at 4:09 AM, then maximum flood 2.1 knots at 6:50 AM.

Air quality for field operations, from the Bay Area Air District's San Francisco Arkansas Street monitoring station. Fine particulate matter, PM2.5, is 8 micrograms per cubic meter, rated good. Ozone is 30 parts per billion. Nitrogen dioxide is 8 parts per billion. For more information visit the Bay Area Air District or openaq.org on the web.

Seismic awareness for emergency communicators: no Bay Area earthquakes of magnitude 2.5 or greater in the past 24 hours. Largest in California in the past 24 hours: magnitude 2.5, near Pinnacles. No earthquakes of magnitude 6 or greater worldwide. Seismic data from earthquake.usgs.gov.

If you smell gas, leave first. Use radios and phones only after you're at a safe distance.