Report

Space weather: solar flux 105, 10 below its 90-day average of 115. 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 3.9 megahertz, so 80 meters is marginal for NVIS. K index 3, unsettled. No significant flares. Data from NOAA.

Lower solar flux means the maximum usable frequency drops, so 20 meters becomes the main daytime DX band, and 40 and 80 meters do more of the work at night.

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, 51 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 7:08 AM, 79 degrees high and 4 percent closer than average, a good time to listen for EME signals on 2 meters and up.

The moon is near perigee, its closest point this month, so EME path loss is near its lowest.

Amateur satellite passes for the next four hours. RS 44, linear transponder, SSB and CW: at 6 AM rising in the north, 65 degrees, overhead. FO 29, linear transponder, on a schedule: at 6:14 AM rising in the southeast, 41 degrees, and at 7:59 AM rising in the south, 39 degrees. PO 101, FM, on a schedule: at 7:15 AM rising in the south southeast, 45 degrees. AO7, linear transponder: at 7:22 AM rising in the north northeast, 46 degrees. For the next pass, RS 44: inverting linear transponder, uplink near 435.64 megahertz lower sideband, downlink near 145.965 upper sideband. 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 12 hours ago: over Oakland, a duct at 260 to 360 meters, good for 70 centimeters 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 4 PM, and the Southern California coast, strongest around 1 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.

Check into a local net this week. Regular net practice is what makes emergency nets work.

Current weather conditions at San Francisco International Airport: All values in SI units. Clear. Temperature 17 degrees Celsius. Dew point 13 degrees Celsius. Relative humidity 77 percent. Wind calm. Barometric pressure 1011 hectopascals, normal. Visibility 16 kilometers.

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

National Weather Service forecast. Values converted to SI units. Overnight: Partly cloudy, with a low around 14 degrees Celsius. Northwest wind around 0.4 meters per second. Saturday: Sunny. High near 30 degrees Celsius, with temperatures falling to around 27 degrees Celsius in the afternoon. North northwest wind 0.9 to 4.5 meters per second. Saturday Night: Mostly clear, with a low around 17 degrees Celsius. West southwest wind 0.4 to 4.0 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 8 seconds, from the northwest. Wind at the buoy 1 meters per second from the northwest. Ocean water temperature 15 degrees Celsius. San Francisco Bay water temperature 19 degrees Celsius. Golden Gate currents: slack water at 7:54 AM, then maximum ebb 0.7 meters per second at 10:19 AM, then slack water at 1 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 5 micrograms per cubic meter, rated good. Ozone is 7 parts per billion. Nitrogen dioxide is 18 parts per billion. For more information visit the Bay Area Air District or openaq.org on the web.

Sign up for your county's emergency alerts, such as Alert SF in San Francisco. Hams are often among the first to relay that information.

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.

After an earthquake, listen before you transmit, and let emergency traffic through first.