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 5, moderate geomagnetic storm. No significant flares. Data from NOAA.

Geomagnetic storms can open aurora on 6 and 2 meters. Point north and listen for raspy, buzzy signals. 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 6:47 PM, day length 11 hours 39 minutes. Moonrise 1:40 AM at 63 degrees, east northeast; moonset 4:16 PM at 293 degrees, west northwest. Waning crescent, 30 percent lit. The Orionid meteor shower peaks Wednesday, October 21, a meteor scatter opportunity on 6 and 2 meters. Moonbounce: the moon peaks today 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.

Grayline enhancement on 80 through 40 meters is strongest within about half an hour of sunrise and sunset.

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: work full duplex if you can, listening to your own downlink, so you don't transmit over others.

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 8 hours ago: Over Oakland, an elevated duct from 100 feet to 800 feet, trapping signals above about 150 megahertz, so 1.25 meters and up. A matching duct over Vandenberg suggests a possible path to Southern California on 1.25 meters and up. K6EEG's experimental tropo forecast, based on NOAA atmospheric model data, for the next 12 hours. Bay Area coast: ducting expected on 2 meters and up, 85 percent. Southern California coast: ducting expected on 70 centimeters, 90 percent; ducting likely on 2 meters, 60 percent. Pacific Northwest coast, peaking around 3 AM: ducting expected on 70 centimeters, 80 percent; a slight chance of ducting on 2 meters, 25 percent. Nothing toward Hawaii.

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

Events. VHF-UHF FT8 Activity Contest, on Wednesday. VHF-UHF FT8 Activity Contest-NA, on Thursday. Arizona QSO Party, this weekend.

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.

Many handhelds can receive NOAA Weather Radio. Program the local channels.

Current weather conditions at San Francisco International Airport: Clear. Temperature 64 degrees Fahrenheit. Dew point 57 degrees Fahrenheit. Relative humidity 77 percent. Wind calm. Barometric pressure 29.94 inches of mercury, normal. Visibility 10 miles.

Know how long your backup power lasts. Test it under real load, not just with a meter.

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 1:42 AM, minus 0.1 feet. High tide at 9 oh 4 AM, 5.0 feet. Low tide at 2 oh 3 PM, 2.8 feet. High tide at 7:49 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 60 degrees Fahrenheit. San Francisco Bay water temperature 67 degrees Fahrenheit. Golden Gate currents: slack water at 4:09 AM, then maximum flood 2.1 knots at 6:50 AM, then slack water at 9:58 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 2 micrograms per cubic meter, rated good. Ozone is 18 parts per billion. Nitrogen dioxide is 7 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.

Know your local emergency net frequencies, and test your radios on battery power regularly.