Report

Space weather: solar flux 105, 10 below its 90-day average of 115. Maximum usable frequency 25 megahertz, measured by the Idaho Falls ionosonde via KC2G: long-distance paths open through 15 meters, 12 meters marginal, 10 meters and up closed. Critical frequency 7.8 megahertz, so 80 and 60 meters are good for NVIS, 40 meters marginal. Daytime absorption limits 160 and 80 meters to short range. K index 1, very quiet. 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 7:07 AM, sunset 6:50 PM, day length 11 hours 43 minutes. Moonset 2:56 PM at 304 degrees, west northwest. No moonrise today. Last quarter moon, 47 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 8:07 AM, 76 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: 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 8 hours ago: over Oakland, a duct at 700 to 1900 feet, good for 2 meters and up. A matching duct over Vandenberg suggests a path to Southern California. K6EEG's experimental tropo model, from NOAA data, for the next 12 hours: Ducting continues along the Bay Area coast, strongest around 6 PM, and the Southern California coast, strongest around 3 PM. Ducting developing along the Pacific Northwest coast after 6 PM. 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, now under way. IARU Region 2 Area GHFSSB Contest, now under way.

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.

Keep your FCC license information current in the ULS, including your email address. The FCC sends license notices by email. Many handhelds can receive NOAA Weather Radio. Program the local channels.

Current weather conditions at San Francisco International Airport: Temperature 72 degrees Fahrenheit. Dew point 63 degrees Fahrenheit. Relative humidity 73 percent. Wind calm. Barometric pressure 29.88 inches of mercury, normal. Visibility 10 miles.

Batteries and radios in parked cars degrade in heat. Keep go-kit batteries somewhere cool.

National Weather Service forecast. This Afternoon: Sunny. High near 86, with temperatures falling to around 79 in the afternoon. Northwest wind 2 to 12 miles per hour. Tonight: Mostly clear, with a low around 62. West wind 0 to 9 miles per hour. Sunday: Partly sunny. High near 83, with temperatures falling to around 75 in the afternoon. Northwest wind 1 to 10 miles per hour.

Tide predictions for today at the San Francisco Embarcadero gauge. High tide at 7:11 AM, 4.4 feet. Low tide at 11:12 AM, 3.5 feet. High tide at 5:11 PM, 5.8 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 4 feet, slight seas, dominant period 15 seconds, from the west northwest. That's long-period ground swell. Wind at the buoy 6 knots from the northwest. Ocean water temperature 60 degrees Fahrenheit. San Francisco Bay water temperature 66 degrees Fahrenheit. Golden Gate currents: slack water at 1 PM, then maximum flood 1.4 knots at 3:44 PM, then slack water at 5:36 PM.

Air quality for field operations, from the Bay Area Air District's San Francisco Arkansas Street monitoring station. Fine particulate matter, PM2.5, is 11 micrograms per cubic meter, rated good. Ozone is 35 parts per billion. Nitrogen dioxide is 17 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 2.9, near South Lake Tahoe. 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.