Report

Space weather: solar flux 105, 10 below its 90-day average of 115. Maximum usable frequency 21 megahertz, measured by the Idaho Falls ionosonde via KC2G: long-distance paths open through 17 meters, 15 meters marginal, 12 meters and up closed. Critical frequency 6.3 megahertz, so 80 and 60 meters are good for NVIS. 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, 45 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.

160 and 80 meters often peak right at sunrise on paths to the west, just before the D layer forms and absorbs them.

Amateur satellite passes for the next four hours. The ISS, FM crossband repeater, when active: at 5:48 PM rising in the northwest, 89 degrees, overhead. AO7, linear transponder: at 6:18 PM rising in the southeast, 56 degrees, and at 8:12 PM rising in the south southwest, 31 degrees. RS 44, linear transponder, SSB and CW: at 6:35 PM rising in the south, 74 degrees, overhead. FO 29, linear transponder, on a schedule: at 7:12 PM rising in the north northeast, 31 degrees. SO 50, FM: at 8:20 PM rising in the north northwest, 44 degrees. PO 101, FM, on a schedule: at 8:31 PM rising in the north northeast, 87 degrees, overhead. For the next pass, the ISS: uplink 145.99 megahertz with a 67 hertz tone, downlink 437.8. Frequencies and live status at amsat.org/status. Pass predictions at n2yo.com.

Satellite tip: the ISSAPRS digipeater is on 145.825 megahertz. Packet stations can send position reports through space.

Tropospheric ducting, from balloon soundings 13 hours ago: over Oakland, a duct at 210 to 560 meters, good for 2 meters and up. A matching duct over Vandenberg suggests a path to Southern California. K6EEG's experimental tropo forecast, based on NOAA atmospheric model data, for the next 12 hours. Bay Area coast, peaking around 2 AM: ducting expected on 70 centimeters, 90 percent; ducting likely on 2 meters, 60 percent. Southern California coast, peaking around 8 PM: ducting expected on 70 centimeters, 80 percent; a chance of ducting on 2 meters, 35 percent. Nothing toward Hawaii.

Tropo openings favor horizontal antennas. For CW, try 144.05 to 144.1 megahertz on 2 meters, and 432.1 on 70 centimeters.

DX cluster and VHF data temporarily unavailable.

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.

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

Current weather conditions at San Francisco International Airport: All values in SI units. Clear. Temperature 31 degrees Celsius. Dew point 12 degrees Celsius. Relative humidity 31 percent. Wind calm. Barometric pressure 1009 hectopascals, low pressure. Visibility 16 kilometers.

Batteries and radios in parked cars degrade in heat. Keep go-kit batteries somewhere cool. Know how long your backup power lasts. Test it under real load, not just with a meter.

National Weather Service forecast. Values converted to SI units. This Afternoon: Sunny. High near 30 degrees Celsius, with temperatures falling to around 26 degrees Celsius in the afternoon. West northwest wind 2.2 to 5.4 meters per second. Tonight: Mostly clear, with a low around 17 degrees Celsius. West wind 0.0 to 4.0 meters per second. Sunday: Partly sunny. High near 28 degrees Celsius, with temperatures falling to around 24 degrees Celsius in the afternoon. Northwest wind 0.4 to 4.5 meters per second.

Tide predictions for today at the San Francisco Embarcadero gauge. High tide at 7:11 AM, 1.35 meters. Low tide at 11:12 AM, 1.08 meters. High tide at 5:11 PM, 1.77 meters.

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 1.2 meters, slight seas, dominant period 7 seconds, from the northwest. Mostly short-period wind waves. Wind at the buoy 6 meters per second from the northwest. Ocean water temperature 16 degrees Celsius. San Francisco Bay water temperature 20 degrees Celsius. Golden Gate currents: slack water at 5:36 PM, then maximum ebb 1.7 meters per second at 9:40 PM, then slack water at 3:01 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 10 micrograms per cubic meter, rated good. Ozone is 53 parts per billion. Nitrogen dioxide is 6 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.